have a 1971 Elcamino with the original 402, and cragers (110,000) Now. I use Goodrich t/a P245X60X15. Can't get over 8,000 miles on the tires. I keep 28 psi all around. By the way I have a 410 rear. Any sugguestions for the proper PSI for these tires. Help!

The more air pressure you have in your tires the cooler your tires will run. You are running those tires at too low a PSI. Those tires call for 44 or 45 PSI, as I recall.

At 28 PSI you are causing the tire to bow in the area of the center of tread, which gives you less tire contact on the pavement. At maximum PSI the portion of tire touching the pavement is only the size of your palm and fingers. If you run at lower than maximum you decrease the size of the footprint, and take away from the vehicles handling ability and ability to shed heat in the form of disipation through the tread.

Running your tires at max. inflation will cause you to loose a little ride comfort, as the tires sidewalls will not want to flex as much, but you will be safer.

Low inflation is most certainly one of the causes for the short life span of your tires. The tire should be run at maximum inflation for 1. Safety 2. Performance.

Also, have you had an alignment done? It may be a dumb question, but it will obviously effect tire life. A wheel alignment is cheap life insurance for your tires.




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"I been chasing a madman for 700 miles."
-Smokey and the Bandit

Sean Thomas
TC Member #907
Sean's Garage (http://www.chevelles.com/showroom/gorbe1.jpg)
70 Chevelle SS 396/350 hp
71 Chevelle SS (clone) 400/450 hp

The max written on the side of the tires is 35 PSI, do you suggest runnning the full 35 pounds, even in Florida?

Yes.

Actually, it's not quite that simple. You need to watch the wear pattern. If the center of the thread is wearing less than the edges, raise the pressure. If the center is showing more wear, lower the pressure.

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Pat Kelley
66 El Camino, daily driver
67 El Camino, STRIP/street
Pat's Page (CR Calculator, Utilites, car specs) (http://cochise.uia.net/pkelley/)

Check your other post on this subject for my response.

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Fred Aldrich
The Chevelle Engineer
Web Site: www.CoreComm.net/~faldrich (http://www.CoreComm.net/~faldrich)

well I run BFGs and the rear tires keep going bald, fronts seem okay

leeds;

what you need to do is adjust your throttle so that your tires don't go up in smoke. http://www.chevelles.com/forum/wink.gif

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Joe Y.
68 malibu (http://www.mindway.com/~drone)
Bloomington/Normal, IL

Quiters never win, winners never quit, but those who never win AND never quit are idiots.

Just out of curiosity, Fred, do you agree or disagree with me on the tire pressure issue?

Gorbe, no offence, but I disagree. The reason I say so is this.

The max pressure is the maximum safe pressure under the maximum rated load capcity of the tire on a specific rim width within a certain temperature range. So any one thing that is not within spec changes the pressure requirements.

You are correct that too low a pressure will cause heat build up and a Firestone type occurence. Also sloppy handling and excessive outer tread wear.

Too high a pressure and you will get poor handling and excessive centre tread wear. Too high a pressure is also dangerous because it cuts down on the contact area of the tire against the asphalt. The centre portion of the tread will bulge very slightly and will take most of the load - this means a reduction in traction of up to 50% and consequently a reduction in braking and cornering ability.

For street driving, the tire pressure should be as high as possible while maintaining a flat contact patch with equal pressure across the tread width. 35psi is probably too high. 28psi is a little low. 30 to 32psi is usually about right. But you need to check the tires on the car. Radials usually have a very slight bulge on the bottom of the sidewall. Drive through a little bit of water and then onto dry pavement. Check the tread width and check the water residue on the treads. This will tell you quite a bit.

This is also why the correct width of rim is very important. With a rim that is to narrow, you have to air down below the safe pressure in order to get a proper contact pattern. With a rim that is too wide, you wind up with too high a pressure. Both are unsafe.

I have 255/60R15's in the back of my car on 15x8's, and I run them at 30psi on the street, my fronts which are 205/70R15's on 15x7's and I run at 32psi. I have normal wear patterns and my tires last a long time. I have 285/75R16's all around on my truck, on 16x7 rims - I should have 16x8's. I run the front at 52psi empty, and the rears at 35psi empty. Loaded I run 65psi all the way around. A friend of mine has the same tires on 16x8 rims. He is able to run 60psi fronts, and 55psi rear - a much better pressure range. Better/longer wear, cooler tires, better gas mileage - only drawback is a slightly stiffer ride.

Hope this answers some questions.

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'67 Chevelle, 388cid, TH350
'85 K20 Silverado 6.2L Diesel, TH400, 3.73

I called our pursuit driving instructor and picked his brain. I have to say that I stand corrected. Using max inflation is for a law enforcement application because of pursuit driving, and may not be (but could be) appropriate for a daily driver. It would depend on what speeds you drive at, and how much performance you need out of the tires.

Sooo.....elcamino1971, it sounds to me like you're having some sort of a problem other than tire pressure.