Correct Tire Pressure after aftermarket wheel install....

[markd79ta]

It depends on the tire manufacturer and tire size as well as how you drive it so I would do some research and find out what is best for your tire type and driving habits. I ran my 245/50/16s at 32psi as a daily driver which was a little above stock but I put 40,000 on two sets with perfect wear (Goodyear GS-Cs and RS-As); 30psi felt horrible to me. I now have 275/40/17s(f):315/35/17s(r), on a limited use vehicle, and I keep them at 35psi as a baseline. When I autocross, I inflate them to 39-42psi depending on temperature...on a 1/4, I drop the back tires to 32-33 depending on track temp; I adjust on subsequent runs depending on what the car is doing. Do a little digging on your tire, and find out the best, and experiment from there. It all kinda depends on what you have and what you are doing and there are thousands of opinions out there so find what works best for you. Additionally, tire pressure also changes the handling characteristics of the car at different speeds so take that into consideration as well. I would imagine that 32-33psi on your 245/45-17s is perfect as a baseline fore daily use, and go from there...you will find that you will change pressures based on what you are doing.

[TandA]

OK, I'm a little confused. I have 275/40/17's, what would the proper pressure be?

[wolfdogs]

Originally posted by TandA
OK, I'm a little confused. I have 275/40/17's, what would the proper pressure be?

this fellow has a Grand Prix...total diff. scenerio man.

look at the door jam, drivers side...tells ya right there. 30psi front and rear.

now........for high speed...35psi. but dont leave them there for everyday driving.

i have found thru my own testing that 32psi front and 30 psi works best on f bodies. the contact patch is the same but it stiffens the sidewall slightly to give better crown edge wear.

[TandA]

My car came with the 16" wheels, but I can still use the 30 psi it says in the door for the 17's? Thanks

[wolfdogs]

Originally posted by TandA
My car came with the 16" wheels, but I can still use the 30 psi it says in the door for the 17's? Thanks

yes.

you have done nothing more that what ASC does when they convert a car like yours to a WS6. the pressure is the same. remember..the 275/40r17 carries more weight than the 16" o.e. tire does at same psi.

[TandA]

Gotcha, Thanks Ken....

[PaganEgyptian]

I am not sure where you get your info, but I have a set of Pirelli 275/40/17 tires that only hold 1433 at 51 PSI!! it has a load index of 93. Much less than your figure of 1500+at 32psi.
I would like to know what kind of super tires you are talking of.
I broke the bead loose of a Goodyear Eagle RSA of a Chevy Police Impalla, during J-Turn manuvers. Sorry to say this, you need to know the tire and the numbers before saying what it can do.
plus the person asking has a grand prix which is FWD not RWD.

[tabahr]

According to Goodyears website a 275/40 ZR17 Eagle F1 GS will hold 1433LBS at 35 PSI. Those Pirellis must be really wimpy. Check out the link.....

http://tires2.digiknow.com/goodyear/...7&sidewall=VSB


Pirelli's load data can be found at ...
http://www.us.pirelli.com/en_US/tyre...productid=2603

Just glancing at the page it doesn't even look like Pirelli makes a 275/40ZR17 tire. Maybe they did in the past. But there 265/40ZR17 tire holds 1565Lbs at 36PSI. That seems pretty reasonable.

[wolfdogs]

Originally posted by PaganEgyptian
I am not sure where you get your info,


INFO: Im a tire engineer, dude. I work for the United States Government. I ran the Federal Tire Qualification program for 13 years. Im the NHTSA liason for the General Services Adminstration. There happens to be a guide that all U.S. Tire manufacturers have to follow, its called the Tire and Rim Handbook. Tire manufactured and sold in the U.S. have to meet the minimums specified in this Document. Europe, Japan, and other countries have simular regulations. The figures come from this book. KenC


but I have a set of Pirelli 275/40/17 tires that only hold 1433 at 51 PSI!!

THEN you got ripped off. LOL. the pressure index in Tire and Rim only goes up to 35psi for that size. and 1433 is max load......at 35psi. passenger car tires dont hold 51 lbs of air........ thats ludacrous. kenC


it has a load index of 93. Much less than your figure of 1500+at 32psi.

SO just what do you think the load index has to do with max carrying load? i kinda think you dont know what load index means, dude! KenC


I would like to know what kind of super tires you are talking of.

IM talking about tire made for sale in the United States of America. kenC



I broke the bead loose of a Goodyear Eagle RSA of a Chevy Police Impalla, during J-Turn manuvers. Sorry to say this, you need to know the tire and the numbers before saying what it can do.

"The tire and the Numbers? heck dude......what are you talking about? and I DO KNOW WHAT THEY CAN DO. if you broke the bead loose, then it was most likely on the skid pad....and thats no comparison to someones running inflation pressures for a public highway automobile. kenC


plus the person asking has a grand prix which is FWD not RWD.


really? dooooooooooooh. i know that.....and i already said that?


take a break dude. you are arguing tires with the wrong person.
pick up a copy of Tire Business magazine sometime....... write the editor.....mention my name.....see what he tells you.

the bottom line is you have given this gentleman incorrect advice on his tire pressures, its not a big deal. your intent to help is appreciated by him and the forum, lets not get all hyped up over it. lets get on with f body stuff and cut the arguments on this one. peace.