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To retrieve OBDII Error codes from your Chrysler/Jeep/Dodge vehicle, do the following sequence with the key: ON-ACC-ON-ACC-ON and look at the odometer, that is where codes will be displayed. Here are the codes that you may/can get. Ho2S = heated oxyen sensor, TP = throttle position, MAF = mass airflow, MAP = manifold absolute pressure, TC=turbocharger. Code|What it means P0030|HO2S Heater Control Circuit Bank 1 Sensor 1 P0031|HO2S Heater Circuit Low Voltage Bank 1 Sensor 1 P0032|HO2S Heater Circuit High Voltage Bank 1 Sensor 1 P0036|HO2S Heater Control Circuit Bank 1 Sensor 2 P0037|HO2S Heater Circuit Low Voltage Bank 1 Sensor 2 P0038|HO2S Heater Circuit High Voltage Bank 1 Sensor 2 P0050|HO2S Heater Circuit Bank 2 Sensor 1 P0051|HO2S Heater Circuit Low Voltage Bank 2 Sensor 1 P0052|HO2S Heater Circuit High Voltage Bank 2 Sensor 1 P0056|HO2S Heater Circuit Bank 2 Sensor 2 P0057|HO2S Heater Circuit Low Voltage Bank 2 Sensor 2 P0058|HO2S Heater Circuit High Voltage Bank 2 Sensor 2 P0100|MAF Sensor Ckt. Insufficient Activity P0101|Mass Air Flow (MAF) Sensor Performance P0102|Mass Air Flow (MAF) Sensor Circuit Low Frequency P0103|Mass Air Flow (MAF) Sensor Circuit High Frequency P0104|Mass Air Flow Circuit Intermittent P0105|MAP Sensor Circuit Insufficient Activity P0106|Manifold Absolute Pressure (MAP) System Performance P0107|Manifold Absolute Pressure (MAP) Sensor Circuit LowVoltage P0108|Manifold Absolute Pressure (MAP) Sensor Circuit High Voltage P0109|Manifold Absolute Pressure Circuit Intermittent P0110|Intake Air Temperature (IAT) Sensor Circuit P0111|Intake Air Temperature (IAT) Sensor Performance P0112|Intake Air Temperature (IAT) Sensor Circuit Low Voltage P0113|Intake Air Temperature (IAT) Sensor Circuit High Voltage P0114|Intake Air Temperature Circuit Intermittent P0115|Engine Coolant Temperature (ECT) Sensor Circuit P0116|Engine Coolant Temperature (ECT) Sensor Performance P0117|Engine Coolant Temperature (ECT) Sensor Circuit LowVoltage P0118|Engine Coolant Temperature (ECT) Sensor Circuit High Voltage P0119|Engine Coolant Temperature Circuit Intermittent P0120|Throttle Position System Performance P0121|Throttle Position Sensor Circuit Insufficient Activity P0122|Throttle Position (TP) Sensor Circuit Low Voltage P0123|Throttle Position (TP) Sensor Circuit High Voltage P0124|Throttle Position Sensor 1 Circuit Intermittent P0125|Engine Coolant Temperature (ECT) Insufficient for Closed Loop Fuel Control P0126|Insufficient Engine Coolant Temperature for StableOperation P0128|Coolant Thermostat P0130|HO2S Circuit Closed Loop (CL) Performance Bank 1 Sensor 1 P0131|HO2S Circuit Low Voltage Bank 1 Sensor 1 P0132|HO2S Circuit High Voltage Bank 1 Sensor 1 P0133|HO2S Slow Response Bank 1 Sensor 1 P0134|HO2S Circuit Insufficient Activity Bank 1 Sensor 1 P0135|HO2S Heater Performance Bank 1 Sensor 1 P0136|HO2S Circuit Bank 1 Sensor 2 P0137|HO2S Circuit Low Voltage Bank 1 Sensor 2 P0138|HO2S Circuit High Voltage Bank 1 Sensor 2 P0139|HO2S Slow Response Bank 1 Sensor 2 P0140|HO2S Circuit Insufficient Activity Bank 1 Sensor 2 P0141|HO2S Heater Performance Bank 1 Sensor 2 P0142|HO2S Circuit Bank 1 Sensor 3 P0143|HO2S Circuit Low Voltage Bank 1 Sensor 3 P0144|HO2S Circuit High Voltage Bank 1 Sensor 3 P0145|HO2S Circuit Bank 1 Sensor 2 Slow Response P0146|HO2S Circuit Insufficient Activity Bank 1 Sensor 3 P0147|HO2S Heater Performance Bank 1 Sensor 3 P0150|HO2S Circuit Closed Loop (CL) Performance Bank 2 Sensor 1 P0150|HO2S Circuit Bank 2 Sensor 1 P0151|HO2S Circuit Low Voltage Bank 2 Sensor 1 P0152|HO2S Circuit High Voltage Bank 2 Sensor 1 P0153|HO2S Slow Response Bank 2 Sensor 1 P0154|HO2S Circuit Insufficient Activity Bank 2 Sensor 1 P0155|HO2S Heater Performance Bank 2 Sensor 1 P0156|HO2S Circuit Bank 2 Sensor 2 P0157|HO2S Circuit Low Voltage Bank 2 Sensor 2 P0158|HO2S Circuit High Voltage Bank 2 Sensor 2 P0159|HO2S Slow Response Bank 2 Sensor 2 P0160|HO2S Circuit Insufficient Activity Bank 2 Sensor 2 P0161|HO2S Heater Performance Bank 2 Sensor 2 P0162|HO2S Circuit Bank 2 Sensor 3 P0163|HO2S Circuit Bank 2 Sensor 3 Low Voltage P0164|HO2S Circuit Bank 2 Sensor 3 High Voltage P0165|HO2S Circuit Bank 2 Sensor 3 Slow Response P0166|HO2S Circuit Bank 2 Sensor 3 No Activity Detected P0167|HO2S Heater Circuit Bank 2 Sensor 3 P0169|Fuel Composition Sensor P0170|Fuel Trim Bank 1 P0171|Fuel Trim System Lean Bank 1 P0172|Fuel Trim System Rich Bank 1 P0173|Fuel Trim Bank 2 P0174|Fuel Trim System Lean Bank 2 P0175|Fuel Trim System Rich Bank 2 P0176|Fuel Composition Sensor Circuit P0177|Fuel Composition Sensor Circuit Performance P0178|Fuel Composition Sensor Circuit Low Voltage P0179|Fuel Composition Sensor Circuit High Voltage P0180|Fuel Temperature Sensor 1 Circuit P0181|Fuel Temp. Sensor 1 Circuit Performance P0182|Fuel Temperature Sensor Circuit Low Voltage P0183|Fuel Temperature Sensor Circuit High Voltage P0184|Fuel Temperature Sensor 1 Circuit Intermittent P0185|Fuel Temperature Sensor 2 Circuit P0186|Fuel Temp. Sensor 2 Circuit Performance P0187|Fuel Temperature Sensor 2 Circuit Low Voltage P0188|Fuel Temperature Sensor 2 Circuit High Voltage P0189|Fuel Temperature Sensor 2 Circuit Intermittent P0190|Fuel Rail Pressure Sensor Circuit P0191|Fuel Rail Pressure Sensor Circuit Performance P0192|Fuel Rail Pressure Sensor Circuit Low Voltage P0193|Fuel Rail Pressure Sensor Circuit High Voltage P0194|Fuel Rail Pressure Sensor Circuit Intermittent P0195|Engine Oil Temperature Sensor P0196|Engine Oil Temperature Sensor Performance P0197|Engine Oil Temperature Sensor Low Voltage P0198|Engine Oil Temperature Sensor High Voltage P0199|Engine Oil Temperature Sensor Intermittent P0200|Injector Control Circuit P0201|Injector 1 Control Circuit P0202|Injector 2 Control Circuit P0203|Injector 3 Control Circuit P0204|Injector 4 Control Circuit P0205|Injector 5 Control Circuit P0206|Injector 6 Control Circuit P0207|Injector 7 Control Circuit P0208|Injector 8 Control Circuit P0209|Injector 9 Control Circuit P0210|Injector 10 Control Circuit P0211|Injector 11 Control Circuit P0212|Injector 12 Control Circuit P0213|Cold Start Injector 1 P0214|Cold Start Injector 2 P0215|Engine Shutoff Control Circuit P0216|Injection Timing Control Circuit P0217|Engine Overtemp Condition P0218|Transmission Fluid Overtemperature P0219|Engine Overspeed Condition P0220|APP Sensor 2 Circuit P0221|APP (Throttle Position) Sensor 2 Circuit Performance P0222|APP (Throttle Position) Sensor 2 Circuit Low Voltage P0223|APP (Throttle Position) Sensor 2 Circuit High Voltage P0224|Throttle Position Sensor 2 Intermittent P0225|APP Sensor 3 Circuit P0226|APP Sensor 3 Circuit Performance P0227|APP Sensor 3 Circuit Low Voltage P0228|APP Sensor 3 Circuit High Voltage P0229|Throttle Position Sensor 3 Intermittent P0230|Fuel Pump Relay Control Circuit P0231|Fuel Pump Feedback Circuit Low Voltage P0232|Fuel Pump Feedback Circuit High Voltage P0233|Fuel Pump Secondary Circuit Intermittent P0234|TC Engine Overboost Condition P0235|Turbocharger Boost Sensor 1 Circuit P0236|TC Boost System P0237|TC Boost Sensor Circuit Low Voltage P0238|TC Boost Sensor Circuit High Voltage P0239|Turbocharger Boost Sensor 2 Circuit P0240|Turbocharger Boost Sensor 2 Performance P0241|Turbocharger Boost Sensor 2 Circuit Low Voltage P0242|Turbocharger Boost Sensor 2 Circuit High Voltage P0243|Turbocharger Wastegate Solenoid 1 P0244|Turbocharger Wastegate Solenoid 1 Performance P0245|Turbocharger Wastegate Solenoid 1 Low Voltage P0246|Turbocharger Wastegate Solenoid 1 High Voltage P0247|Turbocharger Wastegate Solenoid 2 P0248|Turbocharger Wastegate Solenoid 2 Performance P0249|Turbocharger Wastegate Solenoid 2 Low Voltage P0250|Turbocharger Wastegate Solenoid 2 High Voltage

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If your check engine light is on, you can connect a OBDII scanner and retrieve a code. Cross reference that code here to find the source of your problem.

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The fluid capacities of Jeep vehicles

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I found this article interesting and thought I would post it here...I do a lot of reading of different forums and I think I will start copying/pasting interesting or useful pieces over to the Jeepz.om forums, since I like it here and figure that instead of being a fly on the wall, I will add some goodness to the community. I stumbled on this one when trying to google to figure out the optimal tire pressure for my rig on the highway. I probably won't go seeking out a scale to weigh my Jeep and get as detailed as he gets here - but for those that like to get technical - this is probably some good discussion. Original link is from 4wd.com/advisors/tire-wheel-advisor dot aspx (I don't have 5 posts here yet so it won't let me link it for you. hehe) -Poobah Tire and Wheel Advisor by Jim Allen For most Jeepers, a tire upgrade is the biggest trail performance bump for the buildup dollars. It offers improvements in both vital trail performance parameters, traction and clearance. To start, please refer to the Suspension Advisor for more tips on what tire sizes will fit on your Jeep. While you can get an improvement in performance from even a small size upgrade, the benefits multiply as you go bigger… within limits. There comes a place, and it varies from Jeep to Jeep, where the cost, complications and compromises have to be very seriously considered and balanced against your end use of the Jeep. The Tire and Wheel Combo Every tire has a range of rim sizes that will offer the best performance and wear. The rim diameter is a given. A 15 inch tire has to go on a 15 inch rim. Period. With regards to width, the tire manufacturer list a range for a given tire. A 12.50-inch wide LT tire, for example, might show a range of approved rim widths from 8.5-11 inches. Some will show a measuring rim width (MRW), which is the rim size used to obtain the section width specification. A narrower rim will make the tire narrower and a wider one will fatten it up a bit. A good rule-of-thumb is that for every half-inch of rim width larger or smaller than the MRW, the section with will change approximately a quarter inch. This can be useful in fitting a tire that almost fits but rubs a little. The ideal is to make the rim width equal to the MRW, where the manufacturer designed the tire to run. At least stay within the recommended width. If you don’t, squirrelly handling and increased wear could result on the highway. A narrow rim tends to pull the edges of the tread up and away from contact with the road. Too wide tends to make the tread pull up in the center. On the trail, either of these extremes could make the tire more vulnerable to rock damage or being rolled off the rim at low trail pressures. Some Jeepers like to run at the minimum end of the width spec to help protect the rim on the trail. Others think the wider end of the spec is better as it lets the tire flex better. This is one of those controversies where both sides are right… as long as the rim is within the recommended width range. Larger Diameter Rims A recent trend… and a welcome one… is larger diameter 4x4 rims. You can now upgrade from 15 or 16 inch diameter rims to 17, 18 or 20 inch rims. The selection of tires to fit these wheels is growing rapidly. The particular advantage from such a tire/wheel combo comes mostly in the street area. A 37 inch tire on a 15 inch rim has a lot of tire profile (10-11 inches) between the contact patch and the rim. Even when aired up, that makes for a squirrelly tire because the tires tends to roll and flex when braking or cornering. Day to day, with a careful, clued-in driver, that may be livable… except in unexpected emergency situations. The larger rims reduce that profile while keeping the same overall tire diameter and the result is better and more predictable street handling. Many people think the profile of a 33 inch tire on a 15 inch rim, approximately 8-9 inches, is the maximum profile for a tire used day to day on the street. If you run a tire bigger than 35 inches in diameter, you are most in need of a 17-20 inch rim. The downsides are relatively minor and come on the trail side of things. With the reduced air volume of the lower profile tire, you may not be able to air down quite as much for the trail. Most Jeepers with dual-purpose street/trail machines find it an easy compromise. The profile of a 33 offers plenty of room for airing down to get the flex needed for hard ‘wheeling. Only the most hardcore Jeeper needs more, and the odds are his rig isn’t a daily driver. Tread Design This is one of your most critical choices. It will dictate street and trail performance, influence street fuel economy and alter the tire wear equation for the better or worse. The main choice involves evaluating your trail traction needs in the places you most often frequent and balancing them against your street driving needs. Tread design can be broken up into three very basic categories, the street tire, the all-terrain and the mudder. Four if you want to include the rockcrawling variations of the mudder. We won’t talk about street tires at all, other than to say they do the best on the street if that’s what you need. In this case, your 4x4 is likely an all-weather vehicle and you’d want to choose an all season street tire or even a snow rated tire. Mudders and Rock Tires The more aggressive the tread design, generally, the better the trail performance. The open tread design of a mud or rock tire divides the tread into small blocks, leaving many void areas. In mud this makes for a tire with lots of edges that work more or less like paddles. The void areas are open enough that the mud that collects in them can be thrown out via centrifugal force, leaving the tread blocks open to supply grip as they rotate back down into the goo. On rocks, the blocks of tread are more flexible to conform to irregular surfaces and have many biting edges with which to grip the surface. On top of that, the ground pressure on these blocks of tread is high. In some cases, the weight of the Jeep is concentrated on just a few of these tread blocks and are practically “glued” to the rock. What’s the difference between a mud and rock tire? Often very little if we are talking about radials. Most radial mudders perform very well in rocks. Not so much the bias ply. The specialty rock tires differ from a true mudder in way the tread blocks are staggered and aligned and many times are directional. Often, the biggest difference is in the composition of the rubber. Dedicated rock tires often use a softer rubber compound to offer better grip. Grip will be very much better than a standard composition but treadwear will be very much reduced when used on the street. Some rockcrawling tires also use extra plies in the carcass to resist sidewall damage. Aggressive tires have downsides that appear mostly on the street. In the fuel economy department, you may notice a small decrease because they create more rolling resistance. Treadwear will also be reduced according to how aggressive the tread pattern and the rubber compound. They are often noisier as well, though modern tread design has greatly reduced that trend. Finally, street handling is reduced because of the deep, flexible tread designs. Choose a mudder or rack tire if trail performance is your most important consideration. All Terrains “All-Terrain” is a trademarked name used by BFG since the ‘70s but one which has become a generic term for an all-around tire that does “OK” in all venues. There are more and less aggressive ATs but if you find yourself spending most of your time on the street, or in relatively mild trail situations, the all terrain will deliver better MPG and treadwear than a mudder, while offering better handling to boot. Ice and snow performance (on the street) is better as well. With less void area, the AT puts a bit more rubber to the ground than the MT but the tread is more stable and offers more predictable handling. ATs are also quieter than mudders. On the trail, the ATs are at their worst in mud but are good to very good everywhere else. The more open tread AT designs tend to perform better in the dirt and vice versa. The opposite is generally true on the street. Due to improvements in technology, the more open AT tread designs can do much better on the trail than ever before. Tread depth is still usually less than a mudder, even on the more aggressive ATs, so they aren’t quite as flexible in conforming to irregular surfaces. Most times, an AT will outperform an MT in sand. Few ATs will equal an MT in rocks, however. Choose an all terrain if your Jeep gets a substantial amount of street miles or is used in winter climates that have snow. Speaking of snow, there are two tire ratings of interest to those in the snow belt. The first is the old “Mud and Snow” rating (M&S), which was basically the tire manufacturer saying, “Yeah, it’s OK in the snow. Well, obviously, that’s open to some interpretation. The more recent, and useful, rating is ’99 up Winter Tire Traction rating. These tires have to meet an actual winter tire performance standard and those that do are allowed to wear a “snowflake on the mountain” symbol. Many all-season and some all-terrains carry this rating. The Forgotten Tire Any tire can be punctured or cut so a good spare is a vital tool. “Anything that will hold air,” is the common cheapskate’s credo. That’s probably a workable philosophy on the street, where a few miles will carry you to a tire shop. On the trail, replacing a grippy-but-deflated tire with a bald spare reduces your traction potential by as much as 25 percent. You then may struggle on the spots you would normally ace. If the diameter is different than the other tires, you could run into diff and locker issues. An automatic locker goes positively nuts with two different diameter tires and may go bye-bye as a result. Ouch! The best tip… have five identical tires and rims. Include the spare into the rotation process and you will be able to significantly extend the life of any set of tires. Wheel Choices Your two basic wheel choices are aluminum alloy or steel. Steel wheels are tough, malleable and relatively inexpensive, but heavy. Cast or forged alloy wheels are lighter, usually stronger than steel (especially forged) but not as malleable. The malleability aspect come into play when repairing a bent wheel. Alloys are more problematic to repair, though forged units tend to be more forgiving in that regard than cast. The weight of the tire and wheel is the, “Grizzly in the outhouse,” when it comes to tire choices. The increased rotational inertia of bigger tires and wheels puts a larger load on your brakes on the street and reduces handling qualities. On the trail, that inertia adds to drivetrain loads and can help break axle parts. An “average” 33 inch tire weighs about 55 pounds. A stock 225/75-15 tire weighs 28 pounds. Aftermarket steel wheels are usually heavier and stronger than the stock wheels. In averaging a few aftermarket 15x10 inch steel wheels, we’ll use 26 pounds as a number versus about 16 for the stock wheel. So, where the stock wheel and tire combo weighed 44 pounds, a 33 on a 15x10 steel is 81 pounds. An “average” cast alloy wheel (forged are a bit lighter) come in at 16 pounds, dropping the upgraded tire and wheel back down to 71 pounds. There are two basic types of alloy wheels to consider, forged and cast. There are also modular wheels, which usually consist of a cast center section with a spun aluminum rim. These wheels are way-weak for the trail, so avoid them. In the cast realm, there are low-pressure cast wheels and counter pressure, or “vacuum cast,” wheels. The latter system results in a stronger wheel because fewer impurities are introduced into the casting. Forged wheels are the strongest and lightest because the wheel are made from billet material that is rolled or pressed into shape by millions of pounds of pressure. This double forging makes the alloy stronger by tightening it’s grain structure. Beadlocks… Or Not Hardcore Jeepers that run extremely low trail tire pressures often find beadlocks necessary to avoid rolling the tire off the rim. Most beadlocks use a clamped on ring on the outer bead to grip the tire. Others use an inflatable tube inside the tire (with a second valve stem) and some use a spacer that fits between the beads. You don’t see many daily drivers with beadlocks. Part of that is the extra expense and part is the potential problems an owner may encounter. For a trail rig seldom driven on the street, these problems aren’t an issue, but for a daily driven, dual purpose machine, they may be. The first problem to note with most beadlocks is that they are heavier and much harder to get balanced than a standard wheel. Some owners report the clamping ring type beadlocks fail at high speed, causing sudden deflation and parts flying around the highway. There are a still a few do-it-yourself beadlock kits out there that depend greatly on the skill of the welder/fabricator. Many, if not most, beadlock problems can be traced back to human error, either honest mistakes or inexcusable stupidity. Careful owners report good service from most styles of beadlocks but, expense aside, the first choice is to evaluate your needs. If you are seldom in extreme terrain, seldom aired down to extreme levels and drive your Jeep regularly on the street, why deal with the potential downsides? The inflatable beadlocks and the spacer styles, however, seem the most trouble free in a daily driver situation. Backspace, Offset These are two commonly mixed up terms. Backspace is the measurement between the wheel mounting flange and the inside edge of the rim. Offset is the distance from the mounting flange to the exact center of the wheel rim, bead to bead. If the wheel centerline is offset to the outside (away from the axle), the mounting flange moves to the inside and the wheel has negative offset. If the centerline is to the inside, the wheel flange moves outboard and it’s called positive offset. You can determine offset by measuring backspace, subtracting that dimension from the rim width and then dividing by two. An 8 inch rim with 5.5-inch backspacing has a 1.25-inch offset (8.0-5.5=2.5/2=1.25-inches). Remember that rim width is technically from bead to bead, not between the outer edges of the rim. A bigger tire almost always comes with an upgrade to a wider rim. Most times the extra width will be added equally to the inside and outside. That keeps the load on the wheel bearings in the place where the factory intended. A stock 7 inch rim with 3-1/2 inch backspace might be replaced by an 8-inch rim with 3-/3/4 inch backspace. One-half an inch is added to the inside and the other half-inch to the outside. How much you can add to the inside can become a problem on the front, which has to steer, so in some cases, more of the extra width is added to the outside edge, for example, an 8-1/2 inch rim with 3-3/4 inch backspace that has an inch added to the outside. That keeps the backspace the same but changes the offset. Changing the offset a great deal in either direction can cause early wheel bearing failure and tire wear issues. Bolt Pattern Many Jeeps use a small 5 on 4.5-inch pattern. This is fine until you get into large diameter tires. Big and tall tires will focus a lot of stress and strain over that fairly small area and trouble can result. It can appear in the form of broken wheel studs, bent wheel flanges, damage to the wheel at the mounting points, among other things. Many experienced hardcore Jeepers think the 35 inch tire is the point where some consideration should be given towards an upgrade to a 5 on 5.5 inch pattern. Tires over 35 inches, especially on a hard worked Jeep, make an upgrade even more necessary. Since hub conversions are generally an aftermarket product that’s of higher quality than the OE piece, you end up stronger in more ways than just the wheel flange. Eliminating the unit bearing hub found in XJs, YJs and TJs offers one less weak link to offer up as tribute to the Trail Gods. In some cases, you can include a full-float conversion to the rear axle. Wheel Spacers/Adapters A spacer is sometimes necessary to cure minor fitment issues where the alternative is prohibitively expensive. A common example is to correct the offset or backspace of a wheel and tire that’s touching where it shouldn’t. When kept within an inch, that’s an OK option. Keep in mind that the bolts holding the adapter to the hub, which lie unseen under the wheel, can work loose if not properly torqued and regularly checked! Check them a few times after mounting the adapter. Use spacers as a minor corrective device, not so you can use totally unsuitable wheels. A quality spacer or adapter is usually made of billet aluminum and pretty strong but spacing a wheel out some ridiculous amount is potentially dangerous. Tech Tip: Finding Street Pressure For Larger Tires When you increase the tire size, those factory pressure recommendations go right out the window. If your stock 225/75R-15 tire had a 29 psi street rating, the 31x10.50 you replaced it with might need only 22psi to carry the same load. You need a certain volume of air to support a given amount of weight, regardless of the tire size. When you have to carry that weight on a small tire with a small internal volume, you have to really pack it in and this increases pressure. Putting the same volume of air into a larger tire, which has more internal volume, creates less pressure but it carries the same weight. A typical 35 x 12.50-15 might show a maximum load rating of 2550 pounds at 35 psi. That means at 35 psi, those four tires can carry 10,200 pounds, or 5,100 pounds a pair. Your Jeep weighs 4,500 pounds. How much pressure do you need again? There are many ways of finding the new street pressure for a new set of big tires. All involve some trial and error. Here’s one way. Step one is to get your Jeep weighed so you get the front and rear weight separately. Load the Jeep as it’s most often driven, including a full tank of fuel and you. If you want to factor in some different scenarios, weigh it light and then with a capacity load. You can get a vehicle weighed in a variety of places, including the local landfill, grain elevators, scrapyards, and truck scales. Once you have front and rear weights, you need to see the manufacturer’s load vs inflation charts for the exact tire you are using. The tire shop will probably have this information, or can get it. You may also find it on the manufacturer’s website or by calling them. First, divide the weight at each end by two to get the individual weight on each tire. Take the per-tire weight and match it to the chart the get the pressure you need for that weight. If the pounds don’t match exactly, move up to the next higher pressure. These load vs inflation charts will look like the one in the sidebar, which is a generic version for some popular tire sizes from the Tire & Rim Association. You likely won’t weigh side to side but if you did, you might find the tire on one side is loaded more than the other. You can compensate by measuring the tire profiles and adding pressure to the low side until it equals the high one. Take the measurements on flat ground and on smooth concrete. Front and rear weight, and therefore pressure, will also be different because on end of the vehicle is almost always heavier than the other. The final check is the heat test. All tires generate a certain amount of heat running down the highway and this heat will raise the tire pressure somewhat. This is normal. Pressure too low will generate more heat than normal. Check for this by measuring tire pressure after a short, high speed run. You already have your cold pressures. Take a fifteen mile run at highway speeds (55mph and up, but within the speed limit), stop and measure the tire pressure. If you live in a particularly hot area, do this in the morning before the pavement is blistering hot from the sun. If you live in a cold area, do the test in the warmer part of the day or wait for warm weather. Pull over in a safe spot and immediately measure the hot tire pressures. They should be about 10 percent higher than the cold pressures. If they are higher, add a few pounds of air to each pair (front or rear), let the tires cool and repeat until you get the correct results. Tire Load vs Inflation Charts* Each tire is rated differently by manufacturer for maximum load at a given maximum inflation but this chart will give you a general idea of how much weight a given size tire will carry at a lower inflation. Radial Tire Load (pounds) vs Inflation (psi) Charts Tire Size 25psi 30psi 35psi 40psi 45psi 50psi 30/9.50-15LT 1240 1410 1570 1715 1855 1990 33/9.50-15LT 1565 1780 1980 2170 2345 2510 31/10.50-15LT 1400 1595 1775 1945 2100 2250 32/11.50-15LT 1575 1795 1995 2185 2360 2530 33/12.50-15LT 1765 2000 2225 35/12.50-15LT 2015 2295 2555 *This chart was compiled from Tire & Wheel Association Charts and doesn't represent the recommendations of any particular manufacturer. Use it as a general reference.

Jeep Wrangler TJs

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Explaination of the TJ Wrangler diagnostic codes