44 psi tires

[zpiloto]

Originally Posted by brucepick

Nah. Old story. Way way back when I was a young driver there were pics showing various kinds of bad tire wear (including alignment problems etc). Overinflation = more wear in the middle. Underinflation = more wear on the outside.

What they didn't tell you then was that more air pressure = higher FE.

Well I think if Gary says that his tires are wearing in the middle then there probably wearing in the middle. I just want to know what kind of tire he's running because as most folks have alluded to they have no abnormal wear from elevated pressures.

[basjoos]

I have 50,000 miles on my 44psi rated Michilin Harmony tires which I keep at 55 to 60psi. They handle better (less likely to squeal through a hard curve) and have normal treadwear patterns.

[brucepick]

Just bear in mind that when you still have 60-80 % of your tread remaining it's not that easy to see visually if there's more wear in the center. But when it wears down and the center has 2/32" and the outside has 4/32" you can easily see the difference, and its kinda too late.

Years ago I grabbed a tread depth gauge. Just a couple dollars I think, but you might need to go to a real parts store, not a big box store. Or you can use a penny etc., just compare carefully between the different grooves.

[omgwtfbyobbq]

Does anyone know where I could find info on how tire pressure increase w/ heat/speed? That'd settle things, since we could roughly guessimate the pressure needed for the energy in a stock tire at ~55mph to equal the pressure in a tire at the manufacturer's specs, i.e. max pressure/speed/heat.

[psyshack]

Tires dont wear like they use to over all unless under inflated. The bias ply corded tires of years past would wear the center real bad when so called over inflated. Steel belted radials handel the psi diff. And with the over all shorter side wall heights its a diff. game now days.

psy

[Gary Palmer]

Zpiloto: The tires I am running on are Michelins. I am running them on the ultra thin side, at the moment, so I think that is the primary reason I can see more wear on the middle than the edges. I know I am almost down to no tread in the middle and the outside is probably a 1/16 or less.

I switched them from 35psi to 55psi, last year. I was so impressed by how much farther the car rolled when I was coasting out of gear, that I left them at 55. I haven't tried running them at anything less, even though I suspect I could run them lower, to some point and get pretty much the same affect.

The tread wear differential, with the wear in the center of the tread is very acceptable, given that I used to get at least that much treadwear on the edges, anyway. I just haven't been inclined to lower them any, since I drive the car, primarily and it helps enough with mileage, IMO, that I just haven't been inclined to fiddle with anything any lower.

[JanGeo]

Well you are on the high side of pressure but the 44psi max is for COLD pressure and they can get hot and go higher. Also having tread on the sides is better because that is where the water needs more tread to get up from under the tire and where you need tread for cornering. Going straight should be ok with slick centers and when stopping the front tires get more weight transferrred to them so that higher pressure helps them from squeeling which is probably because the recommended pressure is fine until you do have to brake hard and the weight load increases on the tires changing the contact patch and looses traction. At any rate of wear higher pressure should make them last longer but when they are worn out they ARE worn out and you have to get new tires.

[VetteOwner]

the psi in tires increases when they get warm (they get warm from friction between the tire and road, and sun but thats only if they've been sitting in it all day) because of the air inside heats up and expands...

but yea i have noticed that my cars tires even tho thier rated at 35 i have them at 40 or so cold that i see no different wear on the tires.(thier already bald so i might bump it up more to see what happens)

[JanGeo]

Just watch for little buldges in the side walls - cards starting to break inside - could result in a very loud bang!

[Erdrick]

Glad that this topic came up. I have a question about increased pressures. I personally have my car bumped up from a suggested 32 to a more FE-friendly 55. The car handles MUCH better. I didn't expect much of a difference, but it is like I upgraded to better tires as the car now tracks with much more precision. The ride was VERY BAD to begin with, so I haven't even noticed a harsher ride. The fuel economy is looking to have gotten better. I just changed my route (from all city to all rural), so I will have to wait a while longer to see what the real FE effects were.

So, here is my question. Gary has shown that some tires CAN get abnormal wear from overinflation. Is it also possible that the car's suspension also be negatively affected? The tires are directly transferring more vibration from the road through the suspension into the car. Should we expect to have to replace suspension parts earlier than usual if we are running high psi?