Ecomodding > Safety ?

[Blackbird]

Daox -

Illuminating article, but I suggest taking more than one opinion.
I would be looking in the direction of those who try to get every last bit of performance out of their tires.
Racers and autocrossers will always raise the tire pressure beyond the manufacturer's recommendation, but there is definitely an upper limit.
Before someone jumps and says someting to the tune of "but that's with race tires..", this is true also for classes that are required to run street tires.

Originally Posted by trebuchet03

Not the width - that's not how modern tires work (just making sure that's clear)

I was talking about folks who are changing their tires into narrower ones.
Sorry if it wasn't clear.

Originally Posted by trebuchet03

Please also be aware that tire mfr's DO think tires are a place to improve on - as do auto mfr's that want these tires on their cars....

Yes, I'm aware of that.
I'm also fully aware of what horrible POS the Goodyear integrity charcoal donuts that came with my wife's 05 Prius and how much better the car handled when we put some good quality Bridgestones on it.

The decrease in gas mileage was minimal, the improvement in every dynamic aspect of the car was phenomenal.

Originally Posted by trebuchet03

I've also never read in any defensive driving manual (nor heard in any course) of "accelerate and steer" - I've only heard "brake and steer."

Of course you didn't, and your chances to see it in the future are getting smaller by the day.

Modern day cars are made for driving idiots who are clueless about driving physics.
Everything in this current generation of cars is engineered to save the life of the talentless moron that's driving it.
For god sake, there are cars out there that will activate the brakes on their own accord if the engineer that designed the system think that you went too hot into some corner ...

Some drivers, myself included, who have developed their car control skills by taking performance driving courses and lapping racetracks in a variety of cars for some thousands of miles (I logged well over 10K track miles), know that there situations where applying the throttle will do much better than applying the brakes.
I saw many accidents that could have been prevented altogether had the driver sent his foot to the pedal on the right.

Moti

[roflwaffle]

Originally Posted by Blackbird

Well, my guess is that you and everyone else in this thread who says that over inflating wouldn't cause any ill behavior of the car must have missed post #5 in this thread -
http://forum.ecomodder.com/showthread.php?t=764

So I guess someone DOES in fact run enough pressure that results in a significant difference of the contact patch.

I stand corrected, one person ran pressure that wasn't optimal for the conditions and altered that after noting a difference. Still, for the most part I don't think people round these parts don't drive safely. Just compare KE/braking distances and handling ability of someone who's going 55-65mph and getting passed by semis up to someone going 65-85mph on another car's rear end.

[bennelson]

I suppose mods I wouldn't want to do because of fuel efficiency vs safety would be something like removing the airbag to save weight.

Everything is about risk vs reward. You have to weigh the difference.

I know several people who don't have car or drivers license because they feel cars are too dangerous to people and/or the enviroment.

I partly agree and feel that automobiles are sort of a needed evil where I am. Therefore we need to use them as responsibly as possible, balancing safety, performance, and economy.

[Daox]

Inflating tires to or beyond max sidewall pressure I'll agree with you is probably not a good thing IF you do not change your driving habits. However, one of the most important hypermiling techniques is 'driving without brakes' in which you drive as if you don't have brakes. This increases following distances and greatly decreases the chances of accidents. If I had to say, most (not all, as with anything) hypermilers are much more attentive and safer drivers than almost anyone else on the road today. You are right that they teach for 'driving idiots', and therefore that is what we have today.

[DifferentPointofView]

I don't know what your talking about...

when I inflated my tires from about 28psi to 37psi, I didn't notice ANY sort of performance difference. But I saw a HUGE MPG difference because of how much less energy it took to get my giant wall moving. If anything, inflating my tires past the sidewall max (35) actually helped my acceleration times.

Sure, my ride sucked and was bumpier than hell but I went up about 18mpg to 21mpg. that's a lot more miles per tank. And I bet that if I inflated them more I could do even better. But I'm not going crazily over the sidewall, Optimum is supposed to be 33PSI ANYWAY, so 5psi and a little sucky ride takes me a long way.

I think that your trying to make it sound like your cars tires ARE the Most dangerous threat if messed with. The Only time I have seen tire failure is from Under inflation, which overheats the tires and causes blowout and/or completely shredding the tires. Sure, it might grip better on the get go, but I see it as more of a danger when under-inflating than over-inflating.

I also don't understand, because every other day I get passed by a semi, and the only types of tires I see shredded on the side of the road are tires that have been neglected by semi drivers (having to check and inflate 18 wheels seems to me to be a hassle, especially if your in a hurry) and I know this because the treads are so huge, it can't be a car tire.

oh, and an acquaintance from my school died yesterday, he was ran over by a 10 ton truck because his power-steering went out while he was pulling into an intersection. The truck ran up onto his car and crushed the top of it, smashing the cabin. He was pronounced dead at the scene. No joke either.

That is because he neglected to fix problems from his car, and check stuff like that regularly. It was also from poor judgment, and bad driving skills.

The only way I could see tires failing to do their job, even when over-inflated is if they are old-worn out tires that need replacing, but are still on there anyway and being over-inflated. over-inflating will only take what? 1/32 of an inch of width? depending on how severe? I'm not gonna be driving any speeds which my tires would fail from over-inflating, and they're gonna last longer than if they were at 28psi. I'm still gonna over-inflate them, because I know that safety isn't a huge concern here. A huge concern would be my steering, or suspension, or airbag, or mirrors, or windshield wipers. but not how much air is in a tire.

[Lazarus]

Originally Posted by DifferentPointofView

oh, and an acquaintance from my school died yesterday, he was ran over by a 10 ton truck because his power-steering went out while he was pulling into an intersection. The truck ran up onto his car and crushed the top of it, smashing the cabin. He was pronounced dead at the scene. No joke either.

Sorry to here about your friend.

[Frank Lee]

Originally Posted by trebuchet03

Not the width - that's not how modern tires work (just making sure that's clear)

I'm fairly certain that if narrower tires are fitted, contact patch width is reduced.

[brucepick]

Originally Posted by Frank Lee

I'm fairly certain that if narrower tires are fitted, contact patch width is reduced.

Yes and no.
More like no: the shape of the contact patch is changed but contact area should stay the same.

The weight of the car vs. the air pressure creates the contact patch. So if you reduce width the length of the patch would increase if pressure and all else stay the same.

The reason wider tires improves handling is... Well maybe the different shape contact patch will give better control. Lower profile tires on larger rims will have shorter sidewalls - so less flexing is possible. That makes sense.

[Frank Lee]

Yah! What part of "width" did you miss?

[Gone4]

The real solution here is we are all people familiar enough with our cars to be tinkering in the first place. I'm confident all of us should be able to acknowledge when a modification creates unsafe driving conditions and would immediately revert it. It's all about consistently and faithfully testing everything we do, or rather sometimes, abstain from doing).

As someone else said, the biggest danger here is hydroplaning on slush right now, and that can be reduced by having a smaller contact area on your tire. But really, any over inflation significant enough to cause a marked decrease in area contacting the surface on a modern tire is most likely going to burst it.