Bigrahizzl

iTrader: (8)

does the recommended PSi depend on the wheel/tire size???? I dont know what pressure to put in my tires(check specs in sig)

plus1choi

iTrader: (1)

Tire pressure recommended on your door jam is the manufacturer air pressure for your tires regardless what tire brand you run. Most people choose to run a few lbs more which is fine, but you do not want to exceed the MAXIMUM PSI listed on the tire you are using (often it is ~44PSI).

In reply to original posters warning of XL/RF tires. That is referring to vehicles that came with RUNFLAT (RFT) tires. for example most new BMWs all come with RFT tires. These tires are stronger and have stiffer sidewalls which require you to run higher PSI.

I run 36-37PSI on my 1IS and have been pretty happy with that, the 38-39PSI that others have listed they are using sounds perfectly fine as well. I ran the same PSI on my stock 17s and as well when i was on my 18" VS-XX.

Only heavy duty trucks that LOAD a lot of weight need to worry about running those higher PSIs, we're talking about 65-80PSI in each tire. Not to mention they have to using Light Truck (LT spec) specified tires which are made with stronger sidewalls to bear all that weight.

flowrider

iTrader: (9)

Don't think so. Tire markings can be very confusing. RF means Reinforced Tire which is usually associated with an XL (or Extra Load) Tire. The symbol for a Run-Flat Tire is RFT.

If the sizing is proper, the OP should run the tire pressure stated on the door jamb or in the owner's manual. For a firmer ride this can be increased by a lb. or 2.

Lou

plus1choi

iTrader: (1)

sorry you're correct XL/RF does mean extra load or reinforced