Can anyone point me to a definitive reference on adjusting air pressure when changing wheel size? I have heard various different suggestions and guidelines from people in a number of automotive forums regarding adjusting air pressure up or down when going to a different wheel or tire size from OEM, but haven't been able to find anything more than hearsay advice and nothing authoritative. Anybody?

 

I couldn't find exactly what you were looking for but for the most part this will set you on the right track:

Another valuable resource is tire load/inflation tables. Your local Discount Tire/America's Tire should have a copy. Not only will this document tell you the correct tire pressure for stock sizes, but it will provide the information on optional plus sizes as well. A good example would be the findings on a Honda Civic with the stock size 185/65R-14. The recommended air pressure is 28 psi. Plus one size is 195/55R-15 with a recommended air pressure of 32 psi. Plus two size is 205/45R-16 with a recommended air pressure of 36 psi. Note how the air pressure increases with plus sizing to meet the load carrying capacity for the car.

Search for plus sizing charts

 

Jeremy,

As DGC stated, there's no real guideline for adjusting tire pressure per size.

What I have done in the past is contact the tire manufacturer and ask based on my specific sizes.

My Falkens needed 38PSI all around, and now my Vredesteins recommended pressure is 40 to 44 all around.

Sometimes it's best just to ask!

 

Thank you for the advice guys!

 

Regarding your search suggestion DGC, I got some of my desired results but have to sift through a lot of results for large womens' clothing as well!

 

Dont most tires have the recomended pressure on the tire?

 

No, the only pressure number on the sidewall is the maximum inflation pressure which shouldn't be used.

 

i stick with 35-36 psi cold inflated with just about everything.