Not to exceed 150 psi?.....LOL......bicycle tires! (archive)

I asked the 3 series crowd as they run alot of 19" wheels. Most said the same thing. But in a 7 series application I have found that following the doorjambs directions is dead wrong for me. I have 235/35/19 in front and 275/30/19 in rear Yoko AVS sports. I must use 50psi in order to achieve optimum tire wear, and vehicle responsiveness, and tire temperature. Running at 32-35 increases tire temp, tire wear considerably, and vehicle response is muted slightly. These tires are stamped not to exceed 150psi. But each must find out what works for them. You can't get away with following the door jamb. Unless you like to buy tires alot.
I have to disagree with just blindly following the pressure recommendations in the manual/door jamb.

Guy Simpson

Keep in mind these cars were built as long as 13 years ago, and tire construction and composition has obviously changed a great deal since then. Especially when you have upgraded from stock, 15" touring-style type tires, to newer, larger, high performance tires.

Further, any one who has ever run a car on a track or even an autocross can tell you that even if you run exactly the same size and performance level of two different tire brands (e.g. Mich Pilot vs SO2 Pole Position) on the same car, the optimum level of tire grip will likely be found at different pressure levels in the two different brands of tires.

So, does that mean the manual is wrong ..... NO .....but it does mean that its probably not wise to just fill to what the sticker on the door jamb says and forget about it. Especially if you have upgraded the stock wheel/tire combo.

Optimally, you would either test out different inflation levels on your own, or you could get the recommended psi from the tire manufacturer. Where that info is available, I'm not sure, but I am sure (at least for high perf tires) the manufacturers have an "optimal" inflation psi given the curb weight of the car. Then the front/back psi balance can be applied based on the specifics of the E32 (the F/B RATIO in the manual is prob a good place to start)

Just my $0.02

txhedg
'91 750iL
35/35 psi cold
235/45/17 ContiSports

Use the recommended air pressure for the car. The tire size does not change the air pressures. Look on the lower door jamb when you open the drivers door...there should be a sticker with the tire pressure info on it...if it is not there...look in your owners manual.

I have a '91 E32 with Pirelli P7000 235/45-17. What is the preferred tire pressure for these tires on a E32?

Thanks in advance,

--John

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