I just got new Kuhmo Ecstas (H Rates) installed last week, and I was surprised to find the shop only put in 25 PSI into these tires. I went to Kuhmo's website, and it said to use the OEM recommended pressure. I believe the OEM recommended pressure is 35, right? What does everyone else run for the daily driver/weekend autocrosser?

 

I run 712's at 35 psi, what the shop fillem to too-

 

I use about 32-35 during the summer and 30 during the winter.

 

60!!!!!! MWUAHAHAHA....



on my doughnut. I usually run between 32-38psi (205-60-15's).

 

So.... I'm guessing I probably should increase my PSIs...

Thanks guys!

 

50psi on my Falken Azenis

max psi

 

I'm running 42PSI on my Toyos, but only 'cause they roll under at 38PSI. Stupid Toyos!

 

i ran my yokohama intermediats at 50PSi and the wore perfectly

 

they should be around 32-35 psi... which tire shop did you go to?

25 is WAAAAY off. are you sure they balanced your tires to 0:0 too?

 

50 is way to high for the street. Tires will bubble far easier with that much pressure and grip will be reduced since the contact patch won't be fully utilized. Plus, that added air is just dead weight...there is no good reason for such pressures outside of the autocross where some response from the front tires can be gained without side effects since an autocross is a low speed kinda thing. 30-40 psi should be fine for the street depending on your car and driving style.

 

Which toyos do you have? Do you have any proof of this or just personal experience?

 

I'm pretty sure they're balanced properly, as the car rides excellent since I got em. . I told them that I do as much spirited driving as I can get away with, so I'm thinking that's why it's lower... Either that, or someone changed it for something and forgot to put it back? I'll adjust it tomorrow.. no big deal. I figured I"d ask, though, before I get too many miles on them.

 

Tire pressure is entirely dependent on driving style, tires and conditions.

But anything over 40 PSI on a street driven car is crazy and just throwing away money.

Most street driven cars should be run between 26 and 36. Closer to 26-28 PSI if you are interested in comfort or are driving in poor weather conditions. Closer to 34-36 if you are driving spirited or at + 100 MPH.

Too high pressure will result in radical increases in thread wear (even if it is an even amount across the whole tread) and also increases the potential of tire failure due to tread separation.

 

Don't forget that with spirited driving tire temps go up. So if your tires are at max ratings on the tires cold thats definatly not good. Even with sidewall flex your tires will have a hell of a time unseating themselves from the bead at 32 psi. If you really want to know how much air to run when autoxing chalk your tires and see how far the wear reaches up the side wall and adjust accordingly.

 

My kumhos are rated at 42psi. Thats what I try to keep them at too.

 

same here my kummos are at 44 psi all 4 tires. H rated as well.. imm go double check the psi to see if i did it right. because i just put air in them

 

As the profile gets lower, pressure can make a big difference on a cambered wheel.
50 series tires on the negative camber rear will start to loose footprint above ~32 PSI.

For 225/50-16's & stock suspension, I run 28-30 in the rear & 33-35 in the front.
(For Autocross 38 front & 35 rear.)

 

I used to work for Good Year and here is the break down.
The 25 in your case or inside the drivers door on the card is the automobile manufacturers suggested psi(Best ride possible) This is why they sell SUVs with high performance sports car tires.
The 35 (or whatever is the case) is the tire manufacturers suggestied psi(makes the tires last longer and better fuel mileage)
So if you want comfort use 25
If you want better tire life and better fuel economy use the tire manufacturers suggestions. Good Luck

 

Alright, these are the breakdowns i've been looking for

One more question: Why do you guys increase your PSI when you're autocrossing? Wouldn't you want to lower it for better grip??

 

grip is nice, but the higher the psi(not too high) the stiffer the sidewall gets, therefore less flex.

 

That makes sense.. I'm assuming that's not nessicary if you have nice Z rates or slicks, then, right? It seemed like most people were lowering their air pressure at the last one I was at..

 

The pressure ratings on the side of the tire are for max load. This means that you should set a cold tires pressure significantly lower. You guys w/ the Kuhmos, set your tires @ 34 psi when cold and go for a 30 minute spirited drive. Check the pressure again, you will be surprised. For autocrossers, chalk is a good tool for initial setups but a digital pyrometer (I think that is what it is) is best. It's a small inexpensive digital temp unit with a probe. After a run have a buddy take temps at the middle, inner and outer parts of each tire. This will help set tire pressure and suspension settings.

All temps should be very close to each other (within a degree or so front/rear). If the temps are hotter in the center of the tire, lower the pressure. If it's too hot on the inside of the tire the camber is too far negative. If it's too hot on the outside, it's too far positive or the toe is off. Even temps in the right range mean the entire tire is making even contact w/ the ground and you are using as much tire as you can effectively.

 

Here is what I use:

45+ psi on all four for autocross
35 front, 12 rear for drag racing
35 frong, 32 rear for street

Tires are 205/60/15 and the car is an 87 base model.

 

The pressure listed on the tire is the absolute maximum tire pressure that the tire can be run at. This is warm or cold. And remember that the tire pressure will go up when warm.

The sidewall pressure listing is not the recommended pressure at all, and in most cases is considerably higher than should be used on a street driven car.

 

I have stock 15's and autocross allot---I found the best feeling psi is 41-42 front and 32 for the rear. Just feels better