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Tires/Tire pressure


I have a 1988 Jimmy SUV, Sierra Classic 4x4, with 350 V8 & auto tranny. Tires on it are Dunlop 31x10.50R15LT M&S. What is the recommended pressures for this vehicle/tire combo? Door sticker letters have long since faded away & no owners manual present. Mostly driven on highway with occasional off-road use, if helpful. Thank you for your time.


According to Tire Guides, the sticker ought to say ...... ah ...... Mmmmm ..... well, there were quite a few different configurations and quite a few different tire sizes and pressures.

Assuming for the moment that you have a K1500, then it is very likely that you vehicle came with P235/75R15's inflated to 32 psi front and 35 psi rear.  I would check the stick to see if you might be able to discern that it might say that even though it is faded.

In order to carry the same load a P235/75R15 does at 32/35 psi, a 31X10.50R15LT needs to use 47/50 psi.

However, there is one larger problem, and that is the width of the rim.  According to Tire Guides, your vehicle likely came with 6" wide wheels and a 31X10.50R15LT needs a minimum of a 7" wide wheel.   Tires that are used on wheels that are too narrow may wear in the center, and be sensitive to grooves in the pavement and cross winds.

The wheels ought to be stamped on the backside with the width - and it will look sort of like this:  15X6JJ - which mean a 15" diameter, 6" width with a JJ type flange.  


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Barry Smith


I have over 30 years experience in the design, manufacturing, and testing of tires. I have served as the technical advisor to the "800" number. I have authored or co-authored many publications - usually without credit. I can answer almost any technical question, but please don`t ask me to compare brands. I probably have prejudices because of my work experience.


Member SAE (Society of Automotive Engineers) Member Tire Society (Tire Technical Organization) SCCA Regional Competiton License holder Authored many training manuals on tires, their care and use.

SAE (Society of Automotive Engineers) SCCA (Sports Car Club of America) Tire Society

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I am a graduate of the University of Dayton, Dayton, OH - BME, 1971 I attended graduate school at the University of Akron - but did not complete my PhD - something I regret.

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