So my new ride has these huge 20" GfG rims on it....not my first choice, or the second....but it is what it is.

What air pressure is appropriate, the normal pressure that I would run in 18" or is it higher in 20" because of the smaller sidewall?

 

Is there not a recommended tyre pressure label on the underside of the centre console lid?



Graham

 

DOH never thought to look there for 20" tire pressure. Thanks.

 

I have the factory 20" 'Detroit' wheels on my car, and just bought a set of OEM Pirelli's for it this past summer; which I ran all winter with no problems. However, the proper inflation is 32 psi front, 30 psi rear. The label in the armrest has the factory 20" inflation values, and all the other values for the different sized tires that fit your vehicle.

 

32psi is generally a good starting point, but you can increase\decrease it to your taste

 

You're sure to notice a difference with even a pound or 2 change. I was surprised when i looked into the accuracy /precision of most guages. +/- 10% is common. Fyi they sell a reasonably priced model on amazon that is somethinq like 1% accuracy. I use it all the time.

 

If you run the rear tires at more than 28 to 29 psi, you will wear the center tread of both tires down to nothing within 12,000 to 15,000 miles. The front tires can be run at 32 to 33 psi with no such problem....

 

+1

 

I don't know about the 20" tires, but I run my 18s at over 40 psi. I have over 80,000 miles on the rear, and they're just now beginning to need replacement. Now, to be honest, I use the car as a daily driver and long range GT. While I definitely enjoy the handling, but I don't treat her like sports cars. And of course, I don't buy gum-ball tires that will wear out in 15K miles either.

Back to the point though: I run high pressures and haven't experience any unusual wear. If anything, I never had a set of tires wear as uniformly as these have.

 

You are defying conventional physics (or maybe driving on roads made out of cotton *****). I cannot see even the toughest of rear tires on these XK8s delivering more than 45,000 miles even at 28 psi. At more than 40 psi, I cannot see the rear tires lasting even 10,000 miles....

 

I hear ya Jon. I am totally amazed by how long these tires have gone; longer than any other set on any other car. I just had her on the lift yesterday. The wear is completely uniform and the wear strips are just about getting ready to touch the pavement. Maybe I just have a uniquely perfect wheel alignment, but I'll tell you what - There's no way I'm touching ANYTHING back there. And I'm damn-sure ordering the exact same tires!

 

What brand and model are your tires? You may have set a world record for tire durability on an XK8/XKR....

 

They're Fallen Azenis PT722 all season. 255/45-18. I've been quite pleased with them. Even worn, they've stayed very quiet. To be totally honest though, they're not the best on wet roads (but they handled snow OK - lol). Not surprised about the record - like I said, I've never had tires last this long. When do I receive my award? ;-)

 

Never heard of Fallen tires. Did you mean Falken?

 

Oops, .... I didn't catch the Auto Correct. Yup - Falken.