xcanuc

What are you guys running for tire pressures?

I bought a set of 17's and the car started to pull to the left a little bit. So I checked tire pressures and they were 22, 28, 28, and 31. I changed them all to 36 but on my drive to work today the traction control light came on 3 times and I wasn't even driving that hard. It had never came on before on the street and I drove it a lot harder than today.

I drive 30 miles of canyons each way everyday and am a little aggresive. I was thinking maybe 32?

Thanks.
$teve :twisted:

squirrel

Well, I have 215/40-17s, and I'm running 40 psi in my Nitto NeoGens. No problems w/ the traction control light.

Kremtok

That's a lot of pressure! I'm curious, where did you get those numbers from? It just seems such a drastic change from the stock 15" rims suggested pressure of 29 psi.

hnefrdo

i think the 29psi suggested in the manual is wrong..

CBSIMONSEZ

I have the 215/45R17s and had a hell of a shimmy on the front end. I raised the PSI to 37 on the front, and 35 on the rear and no more shimmy. I do have the NanKang tire though, and have over 13K on them, and lately they have been spinning in the wet weather. I think once spring arrives, and i have a little more jingle in my pocket, im going with the Yoko Avid H4s in the same size.

squirrel

The recommended PSI on the sidewall said max psi is 44 psi. I just backed it off 10%. Just my odd way of doing things. But then again, I don't know squat about Scions.

snicka

I believe that you are not supposed to fill your tires up to the max PSI due to the fact that when your tires heat up, the air inside expands which brings up your PSI.

I was told if your tire's max is 44 PSI, you should fill to about 34 -36.

Just repeating what I heard.

Kremtok

Oh, that wasn't an attack of any sort. I'm sure you know what you're talking about, but we were getting our information from different sources. I got 29 psi from the plate on the door jamb of the driver's door. I can see how the pressure should be higher with a lower profile and wider tire. I was just asking if there was any published guidance of what pressures to use for larger tire sizes.

squirrel

Regardless of what pressure you run, according to the tire itrself or what's in the manual, all pressures go up when you start driving. The tire pressures on the tire are for COLD READINGS. You never measure tire PSI when its been driven.

squirrel

Well, look at it this way, the tire pressure on my Trek road bike is 100+psi. The tire pressure on my Fisher MTB is way lower than that.

squirrel

Ok, you guys are right.

I don't know squat about Scions, suspension, intakes, exhaust, tires, handling, driving, ..............................absolutely nothing. I'll just crawl back in my hole.

hotbox05

ah jeez brad. i think you are very scion literate. but i do actually believe you are wrong about the psi thing. the psi on the tire is the max for any loading/car situation. but certain cars require high psi and certain cars require lower psi requirements. i normally just run 32 psi in all of my cars in all of my tires. sometimes i go up to 36psi but more often then not i run 32psi.

TOAST3R

maybe im wrong but i think the best way to find out would be contacting the tire maker and give them the tire and weight of yur vehicle and model n such, abnd see what they recommend?

windowtint

when running a stock size tire - you use the reading that's listed on the CAR, not the tire. When running lower profile tires, you have to run higher than stock size pressures becuase you have less tire sidewall to absorb impact. If you run 32 (factory 60 series) in a 215/35 - first pothole you see will eat your wheel.

hotbox05

bull. i ran 32psi in my 235/45/17's on my supra and no prob at all. but yeah 35's suck ___. waste of money. i'm cool off of spending 150 plus a tire probably alot more like 175 or 200 . waste of money for somethin u gotta replace in like 30k anyways. i'll be runnin 215/40/17 and i'll run 17's and not have a prob. a 205/45/17 will have no prob too. what is that 215/35/18? too much money for rolling stock. too damn big rims for a box too. but it's all good. if u run high psi low pros or not the ride will suffer , u will lose traction and get alot worse wear.

LeeD

What brand and model of tire were you running. That makes a huge difference on how strong a sidewall is. Just stating the sidewall size you can't simily assume the sidewall will be too soft or too hard to threaten the rims.

Typically, the higher performance the tire, the stronger the sidewall. Michialines(sp) typically have very strong sidewalls. Race/Compitition tires have extremely strong sidewalls. You can't roll over a V700 Kuhmo no matter how hard your try, and I've tried.

LeeD

Hey, the first step to helping yourself is admitting to your faults. ; ) j/k

LeeD

As was said before, actually the optimum tire pressure will depend on the car and the tire, and what your looking for. Typically, the "recommended" tire pressure is a good middle ground.

Higher the pressure, stiffer ride, more the tire "balloons", less contact patch, better the milage.
Lower the pressure, more sidewall flex, more comfortable ride, lower milage.

As what was said before, you need to measure tire pressures when COLD. Tire temps can vary the pressure as much as 4-6psi depending on the temp. For consistancies sake, need to always measure cold, or you have to take into account the 4-6psi error.

To really find the ideal tire pressure to run, you need to take tire temp tests with a pyrometer and measure the inner, middle, and outer tread. This will give you an indication of the load the tire's feeling. For the best TRACTION and even wear (may not be everybodies focus) you want fairly even temps, ~+/-10F across the tread.

Example:　If it's hotter on the inside, your inside's going to wear out before your outside.

- If the middle temp is HOTTER than the inner and outer tread temps, then your running too MUCH pressure.
- If the middle temp is COLDER than the inner and outer tead temps, then your running too LITTLE pressure.

If you immediately stop the car after driving and put your hand across the tread, sometime you can feel the temp difference and get a rough idea to do with pressure.

Now, I'm going into this a bit more than what most people would want to know, but just trying to give a little background. To make it easy, just follow what the recommended pressure is. If you've got non-stock sized tires, then I recommend ~5-10psi lower than the max rating. That's just me though and what I've learned from the tires I've dealt with. Squirrel may also be correct in his recommendation on the tires he's delt with. Remember each tire reacts differently with different cars.

The tires I've delt with, raced, and have done tire temps with are, Bridgestone S02, Dunlop SP8000, Kuhmo V700, and Yoko A032R tires on my Z. All of these had different optimal pressures for the best contact patch.


xcanuc,
It's kinda hard w/o knowing what kind of tire you have, but I think you've over inflated the tires, wasn't getting your best tire/road contact patch, hense the tires were slipping easier and you were getting your traction control alarm more frequently. I suggest dropping the pressure 4-5psi.

hotbox05

my fav hi-perf tire is the yokohama avs es100 . ran em in both 225/50/16 on my stock supra rims and then 235/45/17 on my 17's and i will be runnin 215/40/17 on the box. i used to run michelin x-metrics (not hi perf. i know) on my bimmer and loved em.

squirrel

^^^True that!^^^

I wasn't going to get into it that deep since I didn't think they would understand any of the "technical" stuff that peeps who actually race would know and understand. Thanks Lee.