Tyre pressures on aftermarket rims...?

[DamoV6UK]

Chaps

Hoping someone could clear this up for me. On standard wheels/tyres 205/55/15s mazda suggest 28psi all round.

Im changing to 215/40/17s and wondered what the pressures should be...? dont want to wear out my new toyo proxes too quick!!!!!!

Should I keep the same pressures or does it vary on the wheel/tyre setup?

Damo

[Nd4SpdSe]

Personal preference really. You can even go by what's on the tire itself. I have Kumho Mx's up front and Kuhmo Escta 712's on the rear, and I put max in them, 51psi up front and 45 in the rears. I like the responce and handling of the harder tires, and the firmer ride doesn't bother me at all. One thing to consider is that the tire pressure apparently increases if you run it hard, the tires get warm which warm up the air, so the air wants to expand, raising it a few psi, something to consider.

[DamoV6UK]

Yeah youre right about the warming up thing, I heard that if I overinflate them though it will bulge the centre of the tread meaning the middle wears prematurely, dont you find that running 51psi or is that with really high pressures?
Ill have to look on the tyre as well never thought of that

Perhaps if anyone has a good idea of different setups they could do a FAQ for it for clueless types like myself

[jamario]

I put 34 psi on my 215/40/17s Yokohama tires

[jaydog5678]

A general rule of thumb is for every + size in wheel diameter, increase 2 psi. I run 36 all the way around. Never run more than what is indicated on the tire.

[jamesmx3]

old thread i know but, i have 205/40/17, they only have a maximum pressure in the side wall, its like 70psi, i ran them at 35 but they look too low i have put 40 inthe front and the side wall still seems flat looking. any ideas??

[Whisper]

Not aware of any 70 psi tires. Are you sure that's what it says? What tires are these?

Usually 34-36 psi is optimal for most tires of that size. On proper low prifile tires sidewalls are reinforced, so they wouldn't look too flat even if close to deflated. So yeah, more information on the tires would help.

[shameem]

only have a maximum pressure in the side wall, its like 70psi,

[Whisper]

Yeah, as I said. Most street tires of that size that I've seen have a maximum of 44 or 50 psi.

[shameem]

I meant to say that james should look up the normal psi value for his tires and not get confused with with maximum ratings.....

I agree with whisper - the only 50+ psi tires i have seen so far are for RVs, trailers etc.....

[jamesmx3]

checked it out today, whoops sorry for the confusion its maximum 48psi, dont know why i thought it was 70!

I still cant see a normal running pressure though, might stick with 40psi. This should be ok, right? Hopefuly it will not over-inflate through the heat caused by driving, will it?

[Whisper]

Normal daily driving with some highway miles shouldn't add more than 4-5 psi. If you want to be at around 40, you should inflate to 36 cold.

[the_anj]

I try to keep mine at around 50psi that's what the sidewall says for max cold psi, so i usually keep it -2 or 3 psi

[shameem]

You dont have to inflate the tire to the maximum pressure....
The inflation pressure is vehicle specific - does not depend on the tire manufacturer - since the tires can be used in a variety of vehicles the manufacturers specify a maximum pressure that MUST NOT be exceeded for safety reasons - if you routinely inflate to the maximum allowed pressure - you are pushing its limits.

http://www.nhtsa.dot.gov/cars/rules/Tir ... chure.html" onclick="window.open(this.href);return false;
http://www.carcare.org/Tires_Wheels/inflation.shtml" onclick="window.open(this.href);return false;
http://www.tirerack.com/tires/tiretech/ ... p?techid=8" onclick="window.open(this.href);return false;
http://drivers.com/article/354/" onclick="window.open(this.href);return false;
http://www.goodyear.com/cfmx/web/gov/po ... lation.cfm" onclick="window.open(this.href);return false;
http://www.thedieselstop.com/contents/g ... 0Inflation" onclick="window.open(this.href);return false;

[fowljesse]

Not long ago, I read an old thread about this, right here on this great forum.
Here's what you do:
Drive around a little more spirited than usual, with plenty of turns, and stop. Immediately take the temperature of the outermost tread, and the middle of the tread with the kind of gauge that takes surface temps. If the inside is hotter, deflate a little. If the outside is hotter, inflate. Repeat until the temp is even all across the tread.
I run my tires a little over inflated for less rolling resistance, and better gas mileage, but when I start doing AutoX, I will do the above
By the way, with the pressure at about 43, they never get loose, even taking turns 30 mph faster than posted.