Contour Enthusiasts Group Archives Forums Modifications Wheels & Tires tire pressure question

On my Azenis RT215 205/55-16's I run 37 in the front and 34 in the rear, on the street.

When I autocross, while the tires are cold, I put 52psi in the front and 28 in the rear. After 3-4 runs, the fronts are up to about 56-57 and the rears are about 32-34. I usually blead off the rears to keep them around 28-29 after each run though.

These tires are max rated at 51psi at about 1400 lbs load. Since each front corner is about 1000lbs, plus a little more under load, my hot 56 psi fronts are theoretically safe. 4 years of this on this model of tire, sort of prove that

The way azenis are made, they can probably handle a good bit more than the "max" pressure. Especially for short autox use. Do you seriously need that much pressure in the front though? Seems like you'd be losing some time on all but the sharpest corners. Though I reckon if it's working for you, it's fine.

yup... any less than 52, and I start scrubbing the sidewalls. My suspension is stock... hopefully I won't need as much with better suspension.

Running 28 in the rear induces slight oversteer. Though, I added a rear strut tower brace, and I've only run 1 event since adding it, but it made me drift around all the long sweepers... like the 240sx guys. Guess that means I can run a little more psi in the rears now.

Yeah you address the tire issue, but a tire is still gonna roll over without enough pressure (which, especially with STS legal tires, is gonna be more than what you run on the street, atleast on one end of the car). Straight line traction = less pressure. Lots of turning = more pressure.

Also an oversimplication but you get what I mean.

44 the max on my tire that would be a rough ride. im tryin 34 all round i might go down to 32psi. thanks for your replies.

ill post the email when i find it.... i do research thats how i found out, now either the person who wrote the email is wrong ... or you guys are, im not saying you guys are because there is alot of knowledge in these boards, but with the stock tires, or close to like contourfreak is running he wouldnt want to run the max , there not a high performance tire, but with my low profiles i have to run the maxium tire pressure the tire is rated for , like i had said in the other post, its for aftermarket tires it might have been taken wrong and thats probally my bad

The maximum pressure does not depend on the size of the tire, it depends on how much force the tire can take. The pressure you should run is that which keeps the tire flat, with even pressure across the contact patch, under your driving conditions. It also depends on the stiffness of the sidewall of the tires, the weight of the car, and the width of the rim. However, it is never correct to run the maximum inflation pressure for the tire in a general case. With certain sizes of certain tires, you may want as much or more pressure than the max, so that it what you should run. Most tires, if appropriate for the vehicle and rim width, should not be at the max. You may very well need the maximum pressure in your tires, Ed, but it's not a good starting point for the vast majority of people.

I'll leave racing conditions out of this, because people who race have to work with a different set of rules.

For street driving, most tires should be at around 32 psi on a Contour. If you drive hard, and have wider, lower-profile tires with short, stiff sidewalls, you might be able to get up to 40 psi and not see any ill effects. Higher pressures reduce rolling resistance, and even out tire wear under cornering. Lower than 30 psi is too low for just about any Contour with any tire: it's going to make the rubber flex too much, and get hot and worn out. For most tires in most sizes (205/55R16, 215/50R16, 225/45R17, etc.) for the Contour, I'd go with 35 psi all around. If anyone has ever had problems with normal pressures like that, post up and let me know!

If you really want to keep an eye on it: After a few thousand miles, take a ruler with 1/32" or 1mm markings or finer, and see how the wear is progressing. If there's a significant difference between the middle and edges, then you may need to adjust the pressure. However, alignment can cause bad wear, usually on the inside edge, so make sure you're only dealing with one variable.

Agreed. I run 37-38 in the front on the street, because I do tend to take corners fast. When I first tried less than 37, I ended up scrubbing the sidewalls, and the corners were wearing faster than the center. Even with most of my drive to work on the freeway. So all the variables you listed, including driving style. If you don't push the limits of the tires that often, then 32-34 should be fine.

I ran 1 set of kumho mx 225/50-16's, and those I had to run about 35 front, 32-33 rear.

I also rotate my tires every 2 months... or after 2 autocross events.