Tires?

[Danno]

My dinky little 13's from the factory are supposed to be pumped front to back, 31 and 29, accordingly. Now, what would YOU guys recommend for higher mpg?

Which btw, im up to about an average of 29 now

[SVOboy]

What's the tire rated for? (look on the sidewall)

[Compaq888]

If you want safety then go for the max cold tire pressure. It's on the sidewall of the tire like SVOboy said. If your primary concern is mpg only then go 50-55psi. But remember with increased psi there is some loss of traction. Especially with 50-55psi.

[Danno]

Oops.. forgot to reply all this time :X

on the sidewall it says max 35 psi? so im going to fill up to 35 psi on all tires. so i cant really go more without busting a tire?

[kickflipjr]

More, yes. I would go to 40-45psi if it says 35. Some people on this site would go up to 50-60, but that sounds a bit risky to me.

[Ryland]

If your tires are brand new and you don't live around any pot holes, I would say you could go 20% above rated max presure, but as they age, and the rougher the roads you drive on, the more likely they are going to be to the bursting point.
also when you look at your tires, it states a max weight, at the max psi, not just a max psi, the more your car weighs, the more stress the tires are going to be under at a given psi, so if you have a light car that is way under the weight limit of the tires, I would say rasing the presure would be fine, but I would keep it within 20% of the max, and that is part of the reason for buying better tires, mine are rated at a max cold presure of 44psi, next time I'm going to look for ones that are even higher.

[philmcneal]

for me its 10% of sidewall pressure.

I have side bumps for the left of my front and a little on the rear but I turn left a lot with nasty bumps.

Feels hard as a rock!

[krousdb]

Originally Posted by Compaq888

If you want safety then go for the max cold tire pressure. It's on the sidewall of the tire like SVOboy said. If your primary concern is mpg only then go 50-55psi. But remember with increased psi there is some loss of traction. Especially with 50-55psi.

I have read in numerous places that higher pressure increases traction. I am not suffering at all at 60 PSI. I don't remember where it was posted but there was an article about the San Jose Police department seeing better traction with pressure. Also there was a picture of a Ranger riding on two wheels with the pressure at 100 PSI.

[Compaq888]

Originally Posted by krousdb

I have read in numerous places that higher pressure increases traction. I am not suffering at all at 60 PSI. I don't remember where it was posted but there was an article about the San Jose Police department seeing better traction with pressure. Also there was a picture of a Ranger riding on two wheels with the pressure at 100 PSI.

I have read that numerous times. It was on a website for police officers. In the article it stated that the police cars only had the max sidewall pressure. They didn't go more psi for safety reasons. If higher pressure increases traction than why do people at the drag strips lower their tire pressure to gain traction???

[kickflipjr]

I think i said this before, but don't drive with +45psi tirers in the snow! High presure in the snow is a bad idea.

[katman]

Originally Posted by Compaq888

I have read that numerous times. It was on a website for police officers. In the article it stated that the police cars only had the max side-wall pressure. They didn't go more psi for safety reasons. If higher pressure increases traction than why do people at the drag strips lower their tire pressure to gain traction???

With slicks you have to look at the scuff marks on the tire and adjust air to get total coverage. You also aren't going around corners. On the street, the higher pressure will keep that steel belted tread flat on the pavement.

[thisisntjared]

Originally Posted by Compaq888

If higher pressure increases traction than why do people at the drag strips lower their tire pressure to gain traction???

it depends on the traction you are talking about. higher pressure doesnt always increase traction. it all depends on the type of driving and type of tire.

wet driving - max pressure = max traction, the water is pressed out from the tires more efficiently instead of being cupped in the tire.

street driving - dealer recommended pressure is usually best for blending everything(comfort, fuel economy, stearing response, slip angles, etc) yea and as katman with the steal belts, i didnt think of that

drag racing - now keep in mind that everything is tuned for that launch. it depends on the car but any tire thats going to have power sent to it is around 13-20psi depending on the tire(slicks, drag radials, non racing tires) and the tires that will not have power sent to them are usually at the maximum. the two concerns with this are the contact patch and weight transfer. stiff tires have a very small contact patch and allow very little weight transfer. which is exactly what you want for the tires that wont need traction and will have weight either unnecisarily sent to or away from them. the tires that are receiving power are going to want the largest contact patch and be very flexible to weight transfering to or away from them. also as i will get into with auto-x driving lower pressures allow more flex in the tires sidewall and more flex in the sidewall allows a better launch. so when i drag race i put the front to 15-16 and the rear to 44

auto-x - the general rule of thumb for auto-xing and tires pressure is to do what feels right for your driving style in your car. people do all sorts of things. i will explain what i do and why i do it, but keep in mind that its for the way i drive in my front wheel drive car. i am not sure what is best for anyone elses cars. i put the front to 44(maximum) so i have the best steering response. in auto-x the launch usually doesnt mean as much as it does in drag racing, so i will sacrafice it in order to have a more connected feel with the car and what it is doing. the down side to this is that the front tires will give less warning as to when the are going to slide out. so again i do it this way because i know my car. i usually set the rears somewhere just shy of 25. this allows the sidewalls to flex much more. so while it feels pretty loose, in conjuction with the fat rear swaybar, it rear also follows the front through the turns very nicely since the slip angle is increased dramatically with such a low pressure. allowing me to take turns faster.

road racing tire pressures vary from car to car but usually are not as drastic in the difference as auto-xing. but truth be told, i know nothing about it.

i know this is a long post but in the end its almost impossible to explain this without going into suspension theory. i guess ask more questions if you have any.

EDIT: o yea i dont know anything about snow driving either

[katman]

What about ice racing? I can't imagine drilling all of those holes in those tires, then inserting and tightening all those bolts, and then grinding each bolt to a point!

[95metro]

Originally Posted by Compaq888

They didn't go more psi for safety reasons.

I thought it was because the insurance companies asked them not to, not specifically because it was unsafe. They still recommended going over for the savings and actually did it in their driving schools (if I remember correctly).