Over inflated tires.

nixter · 05-01-2005, 11:47 PM

So I recently realised that I've been cruising around with over inflated tires. I never trust the ones attached to the air pump at the gas station so I went out and got my own a while back. I guess I picked a faulty one because just by chance my buddy checked my tires with his and he gets about 10-15 psi over per tire! I'm thinking his is wrong so we check it with the attched one at the pump plus another one that the station attendant had inside. All three say the same thing. Ok, I feel stupid. I've noticed that my car tends to slide around a bit more then it should. I was planning to get new tires even though I still have plenty of tread (they had been stored for a couple years and I suspect hardening), and I still will get new tires but do you suppose some of my sliding was due to lack of rubber contact from too much air pressure??

Cheers,

nik

oldE · 05-02-2005, 02:04 AM

Depending upon the amount of overinflation, there could be several things happening. Uneven tire wear, with the centers being worn away first, is the most common. Some radial tires mask this a bit, depending upon the stiffness of their construction. The sliding you noticed could be due to the tread's inability to conform to the surface of the road, as the higher inflation pressures make the whole tire a more rigid structure. The age of the rubber could certainly contribute to the lack of grip.
Last, you might have experienced less rolling resistance in a straight line. It is doubtful you would have noticed this, but it is an old milage boosting trick, think about narrow racing bicycle tires inflated to 80 PSI.
Les

nixter · 05-02-2005, 07:04 AM

They were over inflated quite a bit unfortunately, like I said 10-15 psi per tire.

Nik

Dantilla · 05-02-2005, 07:10 AM

I see you're in Canada. Your tire guage is probably fine- Just reading metric pounds per square metric inch. That's okay. Porsches are metric anyway.

nixter · 05-02-2005, 08:44 AM

No, they were definately over, my gauge was bad

Dantilla · 05-02-2005, 09:57 AM

The above post was very tounge-in-cheek.

Metric inches?

nixter · 05-02-2005, 10:18 AM

It's way too early in the morning for me to be getting any humour.

nik

Steve87-911 · Steve87-911's Garage

While only slightly on topic, when I was out of town once my wife decided to air up her tires. For some reason she thought her almost new set of tires needed...now sit down for this....78 lbs. of air! On the phone later she commented how easily her car steers now. I bet!
Then she told me how she put 78 lbs. of air in tires designed for 35 lbs. I asked her to let some out until it got to around 35. When I got home I noticed that two of the tires had started shedding the steel belts. The tread had torn away exposing the steel. So we got to replace $400.00 worth of tires about two months after buying them. Good thing she wasn't driving the Carrera!

no substitute · 05-02-2005, 05:15 PM

What size tires, rims are you running and what was the exact pressure?