Tirepressure - 20 inch wheels?

[Dan72]

hey,

what pressure do you guys put into your 20 inch wheels? I'm unable to find any information on this concern...

Greetz,

Dan

[NVRL8R8]

I would still go with what manufacturer recommends. 39 fr, 36 rr. Cold pressure of course.

[willyjp]

hey,

what pressure do you guys put into your 20 inch wheels? I'm unable to find any information on this concern...

Greetz,

Dan

I'd agree with that answer to start with factory recommended pressures, BUT...

what size/aspect ratio tires are you running with your 20's?

are you asking for general road use and/or track use?

as a generality, the LOWER the sidewall height, the stiffer the tire (one reason it's done), and therefore the better the steering compliance (lower "slip" or "tracking angle"--ie: angle of difference between where you point the tire with the steering and where it tracks), sidewall height does that by increasing the relative stiffness, or flex resistance of the sidewall....and increased air pressure does the same.

So, as a very general statement, to equalize handling and ride with a lower sidewall height (higher aspect ratio) you would want to consider DROPPING tire pressures a bit. But you probably don't necessarily WANT TO "equalize" the effects of the bigger wheel, smaller tire....so start the same.

But you may find, especially for track use....where both the handling effect and, fairly soon, the wear pattern effects will become more apparent than in road use, that you need to adjust the handling (see over/under steer table on Tire Rack) or the wear pattern. So you might have to experiment with altering your pressures to get the result (or compromise) that you want.

Obviously you asked for some guidance from the experience of others who've fitted 20" wheels (not me) but I just thought some general guidelines might be helpful.

There is A TON of useful tire tech information on Tire Rack's website, though I couldn't find the direct answer to your question. Also I assume you've verified that your rolling radius is (or isn't) still stock and are figuring on the effects of that. The tire size comparison tool I posted in the tire forum can give you the answer about size change and resulting rolling radius.

http://www.tirerack.com/tires/tiretech/tiretech.jsp

A Couple of Useful Tools for Wheel/Tire fitting

[Dan72]

thanks for the answers...

well, i'm running 245/30/20 and 305/25/20. only for road-use...
actually i'm driving the factory recommended pressures but will try some other pressures in the near future.

anyway, thanks for the good explications, willyjp.