mythbusters tests tyre / tire pressure

[Thymeclock]

Originally Posted by Frank Lee

Frank,

Refer back to post #66.

[Frank Lee]

Originally Posted by Thymeclock

This is well said as both handling and ride are affected by over-inflation.

More than a decade ago I bought an 89 Celica convertible from a private seller. I test drove the car and loved it but I thought it handled a bit oddly. My mechanic inspected it before I bought it and found everything to be OK. But at highway speeds the handling was spooky: uncomfortably unpredictable. Driving it just didn't feel right. After owning it for a day or two I checked the tires and found the tire pressures were close to 50 PSI. I reduced the pressure to about 38 and what a difference it made! It handled just great. I enjoyed the car for 16 years and recently sold it, with it still going strong.

So no, higher pressure is not always better, and it might even be unsafe. And yes, the much harsher ride that comes with over-inflated tires might not make you a happy camper, either.

I've run 50 psi for some time in my F150 and it handles the same as it does with lower pressures, aside from the added bump harshness. I've also run it on other vehicles too and have noted the same thing- handling OK but harshness increased.

Feel free to run your stuff at down to 35 then- I won't badmouth you for that.

Re: 30 mph: On my bicycle and Songi, yes. Others, up to 60 normally, with occasional blasts to 130 mph... or more.

[CapriRacer]

Originally Posted by SentraSE-R

..........While some people think higher inflation pressures increase a tire's risk of failure, there has been no statistical proof presented to support this theory......

I think this addresses your concern.

This is from SAE paper 800087 - The Effect of Inflation Pressure on Bias, Bias-Belted, and Radial Tire Performance - by B. L. Collier and J. T. Warchol, B. F. Goodrich, February, 1980. That image shows the affect inflation pressure has on impact resistance of the 3 types of tires tested. They were all the same: There is about a 30% loss in impact resistance with raising the tire pressure from32 psi to 48 psi.

[Frank Lee]

If I see a 3-5" nub in the road I'll definitely try to avoid it!

Luckily over the last 40 years I don't recall ever encountering one...

Zowie! I want some pants like that!

[SentraSE-R]

+1, CapriRacer.

[Thymeclock]

Originally Posted by Frank Lee

I

Feel free to run your stuff at down to 35 then- I won't badmouth you for that.

My point is that if over-inflating your tires causes your car to handle erratically, that is a safety issue.

Increasing the risk of an accident in trying to save fuel is penny wise, pound foolish. (No pun intended.)

[Fat Charlie]

UFO- I wasn't actually saying that going to the sidewall pressire was "overinflating." Sorry if I made it look like that. I was addressing SentraSE-R's statement that "There's simply no relationship or cause/effect rationale possible." That surprised me enough that it completely bumped from my mind the fact that two posts earlier he said "inflation to sidewall maximum is not overinflation." So that's a sorry to both of you. It turns out that I was agreeing with SentraSE-R even though I thought I wasn't. My point about pressure affecting tire life was referring to tires above sidewall pressure. I singled that out because it's the only environmental parameter that's preset (and the thread topic)- everything else is just driving conditions.

I don't even approach max sidewall with my 215/45/17s because with New England frost heaves being the way they are it'll mean blowouts and failed steering/suspension parts. I sell too many tie rod ends and control arm bushings to people with tall tires at factory pressure settings- I have low tires with and don't feel like damaging my car. My car wants 35F 33R and the sidewall is 44. I'm at 40 all around and don't plan on going higher because I just don't have enough sidewall height to make me feel safe at max sidewall, much less over it.

[Frank Lee]

Originally Posted by Thymeclock

My point is that if over-inflating your tires causes your car to handle erratically, that is a safety issue.

Increasing the risk of an accident in trying to save fuel is penny wise, pound foolish. (No pun intended.)

Well maybe at 50 psi they AREN'T overinflated. It's a YMMV thing.

If I ever get a clapped-out old Toyota, though, I'll keep this in mind.

[Thymeclock]

Originally Posted by Frank Lee

Well maybe at 50 psi they AREN'T overinflated. It's a YMMV thing.

If I ever get a clapped-out old Toyota, though, I'll keep this in mind.

I looked in the glossary but couldn't find "YMMV".

You are good at using vague acronyms and making derogatory comments.

[gone-ot]

Your Milage May Vary = (colloquially) your opinion may be different.