pjpfla

On my old AMG C32, 40 series tires on the 17 inch rims Michelin Pilot XLs had recommended inflation pressures of 34. On the same tires on 18 inch rims on the S4 the recommended inflation pressures are 44. Thoughts? Opinions?

Jet Jockey/A4 Pilot

It depends on a lot of things. If you look inside the door the tire pressure is load dependent.

pjpfla

As someone with track experience, perhaps you can expound on the nuances of higher pressures vs. lower pressures under different settings for us less educated about these things. Thanks.

Bob W.

that's right, nothing.

Reggie

I only go by what the mfrs recommends as a starting point - then I go by feel and tire wear.

pjpfla

...same tire manufacturer, same tire, same series profile, yet 10 lbs difference in recommended pressure (per the door jam label). Do the 18 inch rims need more pressure than 17 inch? Does the all-wheel drive require more tire pressure? Is it because the S4 is a heavier car? And that is what it had to do with the C32.

Inclined

and add to that a close to 4000 lb weight ( tiptronic ) w/o passengers and luggage and you have a set up for bent rims or popped tires . The car also runs to 155 mph before the limiter .
Not surprised for the high oem spec pressures as well as the " XL " ( Extra Load ) sidewall load rating on all the OEM approved S4 tires from Conti,Mich and Dunlop .

Bob W.

Different car, different drivetrain, different weight distribution, different size wheels, different tires, etc. etc. etc. So of course the pressures would be different.

Ray993

Also, was the C32 a 4000 lb vehicle?

pjpfla

C Class 4 doors about 3500 lbs curb weight