So yesterday one of my “non-car friends” was telling me his dad is one of those stupid hypermilers and now he’s trying to get everyone on the hypermiler bandwagon. Anyway, the guy’s dad spent a couple hours fucking with everyone’s tire pressures, “because the manufacture doesn’t know what the pressures really should be”. :meh:
Basically his hypermiler handbook says look at the max PSI rating of the tire and subtract 5 or 6 PSI. In the case of my friends little Saturn Ion, than meant 46 PSI in each tire. Manufactures recommended pressure of 32.
My opinion was he’s compromising safety and tire life for a few bucks in gas and should go kick his dad in the nuts.
Your contact patch is smaller.
The roll resistance of the tire is much less, meaning quicker steering reactions which are great for autocrossing but not real great on the highway for the typical clueless driver.
The tire is going to wear faster in the middle than the edges.
The tire is much more likely to be damaged by pothole or debris impact.
I think making his plastic bodied car less safe was brilliant.
theres no way it should ever be over 5lbs more then what the factory calls for.
Also think of the heat factor, a blow out is probably iminent
See, I’m curious to know roughly how much tire life “over” filling takes away from you.
I’d be surprised if hyper-filling your tires saves you $1 a fillup.
You’re talking about adding extra wear to the tires, and alot of small drivetrain parts… considering that you’re going to use the tires & chassis as often as you’re going to use the gasoline.
I just don’t see it paying out in your favor in the end.
I emailed that to him. But I’m sure his dad will think that’s just some oil company/tire company conspiracy. I mean, he’s dumb enough to think hypermiling is a great idea.
I used to get crazy bitches in their Sequoia’s with 20" rims saying their tire pressure light was on when I worked for Toyota. I’d check them and they’d all be at like 80psi. Damn women.
The quicker steering response is do to the higher cornering stiffness caused by the higher pressure. Resulting in the tire’s ability to produce greater lateral acceleration at lower slip angels. Steering response has nothing to do with rolling resistance. Steering moment (the tires wanting to straighten out or correct the steering wheel) could be related to rolling resistance but not “directly”.
Agree
There is more stress being applied to the ply’s (cords, belts, whatever term you would like to use) at a higher pressure. So it would increase the chances but in most situations if the recommended pressure is not exceeded the chances of damage is negligible.
In my opinion, not supported by facts, the better pressures to run at is about 5 psi above the AUTOMOBILE manufacturer’s suggested pressure found on the door pillar. Better fuel economy, not much increased wear, “sporty” feel, the only down side is decreased ride comfort.
There were two issues with the Explorer incidents.
Ford couldn’t get the Explorer to handle properly so they keep lowering and lowering the rear pressure against Firestone’s suggestion. The final pressure was like 22 psi (way too low for a vehicle of that size).
I got this from a less reliable hear say source: Firestone left out a component in the tire that was identified on the DOT code. Basically the lied about or changed how the tire was made from the initial pass on the DOT test.
In southern climates w/ heat + the ridiculously low pressure Ford was trying to run = fail.
Didn’t mean rolling resistance. I was talking about the tire’s tendancy to roll over on it’s sidewall when making hard steering inputs at manufactures recommended pressures. At 46 PSI the tire isn’t going to roll over much at all, mean any input you give it is going to instantly turn the vehicle. Great if you’re autocrossing, probably not so great for the average driver who isn’t expecting it or used to it.
I usually run my tires about 4 PSI over recommended but no where near the levels these hypermilers are suggesting. No stats to back it up, but after autocrossing for 5 or 6 years now and constantly playing with pressures 4 psi over my door jam rating just “feels” better. For all I know it’s in my head.