Topic: Tire pressure and extra loads?

[safristi]

 

[capriracer]

Maybe that's why most of the tires on my vehicles always seem to wear in the middle rather than the edges. I keep them at the recommended pressure.

This gets pretty complicated:

Many vehicle manufacturers use rims on the narrow side.

Plus drive tires tend to wear in the center, where steer tires tend to wear in the shoulders.

Not to mention that many lower priced tires tend to be designed to be easier to manufacture - which means a rounder tread profile.

Given that radial steel belted tires don't change shape much with inflation pressure.........well.....I think this is just way too complex to assign the wear to just one attribute.

[mar1990]

Plus drive tires tend to wear in the center, where steer tires tend to wear in the shoulders.

Not to mention that many lower priced tires tend to be designed to be easier to manufacture - which means a rounder tread profile.

In lower priced tires, I take it you are referring to OEM tires.  I won't skimp on tires..., but then again I wont buy $200/tire tires either.

If drive tires and steer tires are one in the same (FWD), so it wears evenly? 

[capriracer]

.......In lower priced tires, I take it you are referring to OEM tires.......  

Not necessarily.  What I was referring to was the manufactiring process - particularly the type of mold used.

2 piece molds, where the split is in the center of the tread, are much less expensive to make and maintain.

Segmented molds, where there are radial splits in the mold across the tread face (usually about 7 segments), are much more expensive and costly to maintain, but the tread can be made flatter.

OEM tires can be made either way.

The reason many people think OEM tires are "cheap" is because they wear out so quickly.  This has everything to do with rolling resistance and the vehicle manufacturer's specifications.

From a tire manufacturer's point of view, they don't like the tires to wear so quickly (guess who gets the complaints?).  But if you are delivering a truckload of tires (900 tires) every day to the same location, the assembly lines can be made much more efficient than if you build a couple thousand, then have to change to build a different size for a few days.  Needless to say, vehicle manufacturers get price breaks because of the quantity and the simplicity of manufacture and delivery.

[tpl]

"
The reason many people think OEM tires are "cheap" is because they wear out so quickly.  This has everything to do with rolling resistance and the vehicle manufacturer's specifications.
"
I always thought that the oem tires were ALSO engineered to last for a 3 year 60,000 lease with enough just tread left to pass inspection. 

[Turbo Bob]

My Impreza has a sticker showing tyre pressures for normal or extra loads.  For normal loads I just keep them all about the same (rather than different front and back like it recommends) as it makes the rears a tiny bit over inflated, giving a bit more oversteer. 

[dr_spock]

My VW has a tire pressure value for speeding.     It is higher than driving at the normal speed limit.  (26 psi vs 30 psi)

[capriracer]

.......I always thought that the oem tires were ALSO engineered to last for a 3 year 60,000 lease with enough just tread left to pass inspection.............

I don't know how you could engineer that into a tire.  Tire wear is so highly variable that it is almost impossible to predict without data from the actual usage.

Besides, most of the complaints of tire wear I hear about are on FWD's at about 20,000 miles.  The rears have plenty of tread left, but even if these were properly rotated, you still wouldn't get 60,000!

[UmroAyyar]

.......I always thought that the oem tires were ALSO engineered to last for a 3 year 60,000 lease with enough just tread left to pass inspection.............

I don't know how you could engineer that into a tire.  Tire wear is so highly variable that it is almost impossible to predict without data from the actual usage.

Besides, most of the complaints of tire wear I hear about are on FWD's at about 20,000 miles.  The rears have plenty of tread left, but even if these were properly rotated, you still wouldn't get 60,000!

I changed tires on my 2002 Corolla around 64,000 km just before winter, those were still good for summer driving.

[Squishy]

Hey capriracer, I didn't know you were Canadian -- or are you?  What kind of Canadian talks in miles?  Blasphemy!

All of the OEM tires in my family have actually been replaced due to aging, not tread life.  The tires on my main car, the Escape, were replaced with about 40% tread left, but with 4 years in service they had become so slick that I couldn't drive in the rain.  The Generals that came with our Trans Sport lasted more than 120,000 km and about 8 years before I convinced my parents that it would be a good idea to get them replaced.  I didn't measure the tread depth before they were replaced, but there was still quite a bit of meat before the wear bars.

To me, it would make more sense to manufacture OEM tires to be sticky with a treadwear rating on the mid to low end of non-performance passenger tires.  That way the customer gets a good first impression of the vehicle's handling, and when the tire eventually wears out, they go on the internets and cuss out the tire manufacturer.  The vehicle manufacturer gets all the praise, and none of the blame (except maybe choosing to associate with such a "poor" tire manufacturer).  The only bad press I've heard about Michelin seems to come from OEM fitments.