Over-inflating tires

[mcrews]

Originally Posted by brucepick

For my Civic, I have Kumho all seasons and Michelin (low rolling resistance) winter tires. I run the Michelins in mid-50's psi and the Kumhos in upper 50's. Tread wear has been nice, not going thin at the center as so many have predicted.

This is my second set of Kumho's, and the second set to have side bubbles and supposedly belt separation. No such issues with the more expensive Michelins.

I definitely see fuel economy improvements from increased pressure. I'm also convinced that lower priced tires will have issues regardless of air pressure.

I had bubbles on the second set. 2 of the tires. Only problem I ever had in 4 sets

[euromodder]

Originally Posted by markweatherill

This is received wisdom from the olden days, and is not relevant to radial tyres.

It still happens though.
Even on radials.
I've just about evened out the wear pattern on my Volvo's tyres that way ... It'd wear the shoulders faster when on "recommended" pressure and a bit above, increased pressure (around 51psi) gave more center wear, for an overal even wear

The ride got bumpy around 50 psi on the Volvo wagon.
It gets bumpy around 44 on the little VW up! Ecofuel - and that's got 200 lbs / 100kg of CNG tanks over the rear axle compared to a normal up!

[PaleMelanesian]

Was it actually wearing the center, though? Or was it just wearing evenly, but the shoulders were already worn down so not getting as much contact? My guess it it's wearing the middle because that part is less worn, so it's correcting the previous uneven wear. That's what I observed on two vehicles when I first raised the pressure from the low OEM shoulder-eating level.

[mcrews]

must be pretty stong air in failed belgium..... to make a steel belted tire increase in size. ......you do have steel belts?
want to be on the same page.

[CapriRacer]

Just an FYI:

The belt in a steel belted tire is a layer of parallel steel cables encased in a rubber matrix that runs at about a 15° angle to the circumference. In other words, the steel in the belt is NOT circumferential and does not PREVENT the center of the tread from growing - it only restricts it.

In passenger car tires, there is typically 2 steel belts - one "angle left" and one "angle right" - BUT these 2 belts are insulated from each of by rubber and can move relative to each other.

So as inflation pressure is added, the center of the tread bulges out - a large amount for the first bits of inflation pressure and the amount decreases as more and more pressure is added. The important thing to remember is that it doesn't stop. More inflation pressure results in more growth at the center of the tread - albeit in small increments at higher pressures.

Where this gets complicated is that tire wear is more affected of other things - and some of those things can counter the tire's tendency to wear at the center. Driving style has a major affect. Severe cornering tends to wear the shoulders of the tread. So if you combine strong cornering with high inflation pressure, the result could be even tread wear.

Plus, the construction of a tire (meaning the flatness of the belt relative to the loaded profile within the tire's structure) can affect the evenness of wear - and tire manufacturers do adjust this as they get data from their returns. It is not uncommon for some radial tires to develop shoulder wear due to poor placement of the belts - but fixing these sorts of things requires increased cost and increased rolling resistance - and sometimes that is not acceptable.

Put a different way, tires aren't always designed to wear evenly. In many cases, uneven wear results in things that are more desirable. For example, tires supplied to vehicle manufacturers have to meet rolling resistance requirements and since these tires don't carry a treadwear warranty, it's OK if they wear out in the shoulders first. In fact, one of the tricks tire engineers use to get low rolling resistance is to take rubber out of the shoulder - and that results in worse shoulder wear.


Bottomline: Increasing inflation pressure TENDS to cause wear in the center of the tread, but there are enough other factors that can overwhelm this tendency - so you need a large sample size to see this tendency.

[hat_man]

These are not top of the line Michelien's or Goodyear's just some average off brand that were supposed to be equivalent to Cooper Tires. I run these anywhere from 42-48 psi (cold) with a 44 psi max listed on the tire. Maybe it's from being an off brand or maybe the construction but the two rear tires are wearing the same respectively, thin in the center. The pictures are of the the left and right rear tires. Vehicle is the Ranger listed in my signature and no I do not tow anything and only haul 50-100 lbs of stuff and only on occasion. Most of the time it is empty.

[YukonCornelius]

I was just looking at the Michelien's on the back of my friends 08 ram last night. Same tread pattern, they wore the same way but he is no ecomodder.

Originally Posted by hat_man

These are not top of the line Michelien's or Goodyear's just some average off brand that were supposed to be equivalent to Cooper Tires. I run these anywhere from 42-48 psi (cold) with a 44 psi max listed on the tire. Maybe it's from being an off brand or maybe the construction but the two rear tires are wearing the same respectively, thin in the center. The pictures are of the the left and right rear tires. Vehicle is the Ranger listed in my signature and no I do not tow anything and only haul 50-100 lbs of stuff and only on occasion. Most of the time it is empty.

[2000mc]

I believe you will see that tread wear at the rear on most vehicles with a solid rear axle

[PaleMelanesian]

That's just perfect for a tire rotation. Put those on the front where the shoulders wear down from cornering, put the corner-worn fronts out back and they'll all wear back to even soon. And, you have better cornering grip.

[ksa8907]

Trucks will wear thin at the center because trucks are inherently light over the rear axle. Just to add to the thread, I have 2 hankook and 2 cheap kelly tires and run them at the listed max of 44psi. I don't have irregular wear.