Storm chasing Tires

[Dennis Sherrod]

Tire Pressure versus Gas Mileage.
Trying to remember some of what I read not too terribly long ago...

I believe the figures were like 3% better gas mileage with proper tire inflation.

Less than proper tire pressure in all 4 tires was 0.4% drop in gas mileage for every 1 psi under inflation.

These numbers really add up to a substantial amount based on several hundred miles and the mpg you get now on various vehicles.
Even at only 15 mpg, a 4% loss amounts to almost 0.6 mpg. Every 25 gallons saves 1 gallon of gas. Average $3.35 gallon. Higher MPG vehicles makes a bigger mpg drop when under inflated.

I definitely keep mine checked.

 

[Greg Campbell]

Tire Pressure versus Gas Mileage.
Trying to remember some of what I read not too terribly long ago...

I believe the figures were like 3% better gas mileage with proper tire inflation.

Less than proper tire pressure in all 4 tires was 0.4% drop in gas mileage for every 1 psi under inflation.

These numbers really add up to a substantial amount based on several hundred miles and the mpg you get now on various vehicles.
Even at only 15 mpg, a 4% loss amounts to almost 0.6 mpg. Every 25 gallons saves 1 gallon of gas. Average $3.35 gallon. Higher MPG vehicles makes a bigger mpg drop when under inflated.

I definitely keep mine checked.

You might try over-inflating the tires a few PSI. You probably won't gain a huge amount - as you pass through the zone of proper inflation, the rolling resistance curve starts to flatten out; it penalizes under-inflated tires more strongly than it rewards over-inflation. Still, you can likely squeeze a few % mileage increase out of the car.

My own car actually wears the tires unevenly if I try to maintain Honda's suggested 33 PSI. I've been at 38 for a year and the tires wear is perfectly balanced.

One thing: Make SURE the tires are stone cold when measuring pressures. Even a short trip to the corner gas station will elevate the pressure by several PSI, resulting in underinflation.

-Greg

 

[Jerry Prsha]

You might try over-inflating the tires a few PSI. You probably won't gain a huge amount - as you pass through the zone of proper inflation, the rolling resistance curve starts to flatten out; it penalizes under-inflated tires more strongly than it rewards over-inflation. Still, you can likely squeeze a few % mileage increase out of the car.
-Greg

Not a good idea. You'll be making your tires round on the bottom causing less surface contact in wet conditions and also will wear out the main part of the tread in the center of the tire much more quickly.

 

[Greg Campbell]

Not a good idea. You'll be making your tires round on the bottom causing less surface contact in wet conditions and also will wear out the main part of the tread in the center of the tire much more quickly.

Nope. You want a smaller footprint in wet conditions. This gives you higher pressure in the contact zone between road and tire, forcing water out and allowing the tread to contact the road.

 

[Jerry Prsha]

Nope. You want a smaller footprint in wet conditions. This gives you higher pressure in the contact zone between road and tire, forcing water out and allowing the tread to contact the road.

Sorry I disagree. If that were the case, we'd all be driving on bicycle tires. The more friction you have the more they hold. Aquatreds and such have channels to direct the water away from under the tire so that more contact is made with he surface of the road, By limiting your contact, you're floating which is dangerous.. Like hydroplaning. You lose that needed contact in turns.

Look at a boat hull's shape. The water is directed to the sides which raises the hull higher. You don't want your car lifted on a wet road.

 

[Jason Boggs]

Here is a good little read on hydroplaning from Wikipedia. From what it says here, Greg is right on with what he is saying. Actually, I thought that the more contact the tire has with the road, the better it was against hydroplaning.

HYDROPLANING

 

[Jerry Prsha]

Here is a good little read on hydroplaning from Wikipedia. From what it says here, Greg is right on with what he is saying. Actually, I thought that the more contact the tire has with the road, the better it was against hydroplaning.

HYDROPLANING

The article says to over-inflate your tires? I don't think so.

All articles I've read say to inflate to maximum but it all depends on the amount of tread on your tires to raise you above the water and direct it away from under the tire.

If you have slick tires already, go ahead and over-inflate them. You're screwed anyway.. hehehe

 

[Jay McCoy]

Its not always about directing water away from your tire. Think of your tire as a wing and the water as air. You want a smaller surface to cut through the air. A wide flat tire will actually ride on top of the water like a wing on air. Thats what causes hydroplaning. You want a heavier small surface to "cut" through the water to the surface. Same effects as mud or sand but in reverse. You lower your pressure to widen your surface area so you can float on top of the mud instead of cutting deep into it and getting stuck.

If you take a wide corvette tire and a skinny tire off a yugo the yugo tire will outperform the vette in a hydroplaning test.

 

[Patrick Martin]

I'll throw a vote for the Bridgestone Dueller A/T Revo. The first set on my wife's SUV lasted 55k miles. It was a no brainer to replace them with another set. Fantastic all around A/T tire!

I go 1lb over the reccomended pressure on my Accord in winter, but stick with the reccomended pressure in warm weather. I'm at 50k miles and still on the original Michellin MXV4 tires that came on it. Even though the wear is great, I personally hate these tires. Wear is completely even and at the end of the summer will replace with something else. I don't reccomend going way over on pressures. Remember that you also build pressure in a tire as you drive on it and having a tire significantly over inflated will compromise ride and handling.

My wife's SUV has reccomended pressures of 28psi, and it once came home from the dealer with 40psi after they "set" the pressures. It was like driving with bricks for tires. Needless to say my instruction to them any time it's in for service is to not touch the air pressures. I set my own cold pressures at home every other week.

 

[Jerry Prsha]

I stopped in and spoke with my tire dealer and presented this issue to them. They laughed and said, "WHy would you over inflate your tires?" ..Thinking that I was the one wanting to do this. They said not only would you wear out your tires by cupping the bottom, it was a very dangerous situation where you'd lose contact and possibly slide off the road because there was less traction.

Hmmm.. Where have I heard that before? heheh

Seriously.. I'm concerned that by posting this, you're going to put someone's life in danger. Running them low just wastes gasoline...

I'm done posting on this.. Beating the dead horse and all...

 

[Greg Campbell]

As if ANYONE on this forum is gonna listen to me?

More rubber on the road will increase raw grip when driving on a dry, clean, grippy surface. In these conditions, the tire slides due to physical tearing of the rubber. More rubber can resist more force before tearing.

On a wet road, at least with regard to hydroplaning, keeping the tire from floating it all that matters. Higher road pressure is everything.

Just for argument's sake, I don't consider my tires 'overinflated.' Car manufacturers' suggested inflation pressures are an ugly compromise between tire longevity, gas mileage, ride quality, and who-knows-what other factors. IMO, Honda blew it. Running the suggested 33psi gives a notably softer ride... and generates notably uneven tread wear! I started regularly measuring my tire tread when I got a new set, about a years ago. After running a few months at 35psi, the tires were wearing slightly more at the edges. I suspect that 36~37 is neutral. I'm at 38~39 to equalize the residual tread thickness irregularity, and because I'm chasing that last 0.02 MPG.

The tires are not cupping, and I have yet to kill myself. I think I can feel a little less grip on those rare occasions when I do mildly illegal things on curvy backroads. On the other hand, the increased pressure definitely improves overall handling. The tires seem more predictable, they break loose more gradually and slide in a controlled fashion. Steering is more precise, and driving is more fun.

 

[Gerard Jebaily]

Its not always about directing water away from your tire. Think of your tire as a wing and the water as air. You want a smaller surface to cut through the air. A wide flat tire will actually ride on top of the water like a wing on air. Thats what causes hydroplaning. You want a heavier small surface to "cut" through the water to the surface. Same effects as mud or sand but in reverse. You lower your pressure to widen your surface area so you can float on top of the mud instead of cutting deep into it and getting stuck.

If you take a wide corvette tire and a skinny tire off a yugo the yugo tire will outperform the vette in a hydroplaning test.

This makes sense, but ive been more worried about loosing traction on just a wet road when having to slam on brakes for (insert reason here). Last thing i wanna do is need to stop quickly and have my brakes lock up and tires skid. It seems logical to have more tread on the road for something like that. So while over inflating your tires can help with hydroplaning, proper inflation has been the name of the game for me to prevent skidding.

 

[JF Massicotte]

If I remember my physic courses right, a larger surface on the road will NOT improve friction. Friction is a function of material and weight. A small surface will offer same friction if the material and weight is the same.


I think the only reason we use larger tires is that larger tires can handle a heavier charge and will offer better resistance when they have to hold axial forces.


Maybe I am wrong maybe I am right, anyone can confirm?



Back to tires, I am probably going into Michelin for my 2001 Ford Escape. Any better option?