Tires: Tire Air Pressure, goodyear fortera tripletred, correct tire pressure

Question
QUESTION: I just purchased 4 new Goodyear Fortera TripleTred tires size P255/70R16 for my Jeep Liberty. (OEM Tires 255/75R16)What is the correct tire pressure that I should use recommended by Goodyear? Jeep recommends 33 psi but the on the sticker inside drivers door but the low air pressure warning light stays on at this pressure?

ANSWER: Pete,

I've looked at a reference book, and I do not find that any Jeep originally came with P255/75R16's.

So our first task is to check the vehicle placard again to see if that is indeed the correct tire size.  BTW, the pressure listed on the placard is supposed to be for the original tire size as listed on the placard.  If you change tire size, then the proper pressure will change, too.

I suspect the placard says P225/75R16. Assuming that would be correct, then you could use as low as 26 psi.  However, I suspect your vehicle's TPMS measures pressure directly (as opposed to an indirect system, which measures differences in diameter.) and that means it will always go off at 26 psi.

But I suspect the real reason you are getting the light is one of the following:

1)  The vehicle has not been reprogrammed following the tire exchange.  I don't know how Jeep does that, but you should be able to get an answer from the owners manual or directly from Jeep.

2)  The pressure gauge you are using is reading high.  Try a few more psi and see if that helps.

3)  The sensor in the wheel has been damaged.  The folks at Jeep should be able to tell you what sort of indication you should get if one is damaged.

Hope this helps.



---------- FOLLOW-UP ----------

QUESTION: Im sorry the OEM Tire Size is 225/75R16. The tire pressure placard from Jeep recommends 33 lbs for the OEM Tire size. All the tire shops recommend 36-40 lbs for my new larger size tires 255/70R16? Just wish I could get info from Goodyear so I do not prematurely wear the tires out with too much pressure? All I can find from Goodyear is to use "Manufactures Recommended Pressure" but that is for OEM size tires? Anything below 33 lbs and the low tire indicator stays lit.

Answer
Pete,

Thanks for the reply.

The reason Goodyear recommends the the "Manufacturers Recommended Pressure" - meaning the vehicle manufacturer AND the original tire size - is that 1)  the vehicle manufacturer is the one who understands WHY that pressure was recommended and 2)  to do otherwise not only confuses the situation, but also Goodyear has no reason to contradict that.

So look at the 3 items I listed and see where that leads you.