hi my normal stock tire size is 205 60 15's and the pressure suppose to be 31 PSI in the front, 34 PSI in the rear. My point is that i'm running 215 60 15's should i put the pound pressure like i said above? Thanks
it really depends, when you put on a aftermarket set of tires you should usally put in the maxium tire pressure, the pressure the factory puts on there is for the best ride, but this has been a debate for a little while, ive heard both sides of the arguement, but i myself would put in the maxium tire pressure
Originally posted by SvtEdwardo420:
it really depends, when you put on a aftermarket set of tires you should usally put in the maxium tire pressure, the pressure the factory puts on there is for the best ride, but this has been a debate for a little while, ive heard both sides of the arguement, but i myself would put in the maxium tire pressure
WRONG
Start off with something like 34 all around. See how much contact patch the tires are getting and how they feel, adjust from there. As time goes on, watch how they wear.
No im not wrong and either are you, the maxium tire pressure rating on the tire is what your supposed to run , anything over that is considered overinflation and a significant amount under is underinflation, ive sent email to good year and toyo about this becuase i had an arguement with the techs at my shop about it, now this is with after market tires, like how i put 18's on my car with low profile tires, how do i know how much air to put it? i put in the maxium tire pressure,like i said in my last post the factory puts the tire ratingd for the most comfortable ride, even though it might wear a little premature, but when you put 32 psi in a tire your almost at the max of the tire anyeay, usally 40. so dont tell me im wrong, unless you have something to back it up. thank you
The pressure printed on the side of the tire is the maximum safe tire pressure, not what you should be running. The pressure inside the tire should never match or exceed the pressure printed on the side.
Originally posted by SvtEdwardo420:
No im not wrong and either are you, the maxium tire pressure rating on the tire is what your supposed to run , anything over that is considered overinflation and a significant amount under is underinflation, ive sent email to good year and toyo about this becuase i had an arguement with the techs at my shop about it, now this is with after market tires, like how i put 18's on my car with low profile tires, how do i know how much air to put it? i put in the maxium tire pressure,like i said in my last post the factory puts the tire ratingd for the most comfortable ride, even though it might wear a little premature, but when you put 32 psi in a tire your almost at the max of the tire anyeay, usally 40. so dont tell me im wrong, unless you have something to back it up. thank you
Everyone with knowledge about tires will back me up buddy (including myself and everyone else that works with me at a goodyear shop).
So, my tires have a 51psi maximum pressure. You're saying I should run that? So even though not nearly the whole tire would be making contact with the road, I should still do it? Even though the center of the tire would be wearing much quicker than the rest of the tire, I should still do it because you say so? Do a little research buddy. Thank you.
Originally posted by Matt R:
The pressure printed on the side of the tire is the maximum safe tire pressure, not what you should be running. The pressure inside the tire should never match or exceed the pressure printed on the side.
This is basically correct. Running 41 lbs on a tire that has a maximum of 41 lbs listed on the sidewall is insane. It will ride rougher than a truck and the center portion of the tread will wear out way too fast while leaving reasonable tread on the outside edges.
The sidewall maximum is a cold reading. It can go above that when hot. It would only be appropriate when the car has a heavy load or when the tire is undersized for the car.
Often, the tire maker will have a recommended tire pressure. It may be found in their catalog. Usually I pay attention to the tire makers suggestions and the automakers suggestions and come up with my own, which I alter as the tire wears as well as from experience as I drive. Most of the time I start with about 2 lbs above the automaker's recommendations.
As the tire wears you can see if it is wearing evenly across the face of the tire. If it is wearing more toward the center of the tread, lower the pressure a little. If the outside edges are wearing more, raise the pressure a little.
Usually you will use a little more pressure on the street than you will on the track autoX.
Originally posted by Big Jim:
Usually you will use a little more pressure on the street than you will on the track autoX.
You mean a little less on the street than at autox right?
More for autox to prevent tire rollover.
Originally posted by Big Jim:
Usually you will use a little more pressure on the street than you will on the track autoX.
Ed, and a little more pressure usually means 1 to 2 PSI more of the recommended tire pressure, NOT 5 to 10 PSI more. 
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.
Originally posted by Kremithefrog:
Originally posted by Big Jim:
Usually you will use a little more pressure on the street than you will on the track autoX.
You mean a little less on the street than at autox right?
More for autox to prevent tire rollover.
I ment what I said, but now I realize that it is a grose oversimplification.
The idea is that in racing circumstances you usually want a stickier tire. Hopefully you have already addressed using a tire that isn't likely to roll over on turns. The most important thing is that for racing you dial in the pressure according to how it drives on the track.
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
Originally posted by SvtEdwardo420:
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
i have the cooper cobra GT tires
[image]http://coopertires.com/us/en/displaylarge.asp?file=cobraGT.jpg&name=Cobra+Radial+G/T[/image]
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.
Originally posted by morbid:
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.
sounds good to me. but i dont get why is the back require more pressure then in the front on the contours?
Originally posted by contourfreak22:
Originally posted by morbid:
about 35 front, 32-33 rear.
sounds good to me. but i dont get why is the back require more pressure then in the front on the contours?
It doesn't. The rear requires less because there is less weight on it. However, you can keep them the same with no problems on the street.
the 185 70 14 and the 195 65 14 requires 34psi all around. the 205 60 15's says 31psi in the fron and 34 in the rear. thats what the sticker says on the door. but im gonna go with 32 psi right now and i'll watch the tires for wearness.
That doesn't really make sense, unless they're assuming everyone will be driving around with 1000lbs or more in their trunks. As soon as you start putting more than 32psi in the rear, you'll see the contact patch begin to shrink.
yup i dunno the sticker weird
Originally posted by contourfreak22:
the 185 70 14 and the 195 65 14 requires 34psi all around. the 205 60 15's says 31psi in the fron and 34 in the rear. thats what the sticker says on the door. but im gonna go with 32 psi right now and i'll watch the tires for wearness.
My contour w/ 185/70/14 says 32 all around.
I'm not sure about how they decided it for the contours but sometimes the manufacturer has pressures listed for half load or full load.
Another example of door jam stickers vs reality:
I put Falken Ziex tires on my wifes Intrepid. I left them at the door jam specified (and Discount Tire filled) 32psi. After about 6 months, it was apparent that 32 was WAY too low for those tires, as the shoulders were wearing fast. Had the alignment checked, and it was good. I've since upped her tires to 37 front, 34 rear, and they seem to be wearing a little better. It might be a little too much, but it'll help even out the tire wear (put more wear on the center).
Big Jim... when I meant the pressure inside the tire should never exceed the pressure on the side, I was refering to it being cold. Just to clarify.