Tire Pressure

[jadatis]

The 35/36 psi for standard load is called the reference-pressure, for XL/EXTRALOAD/ REINFORCED reference pressure is 41psi ( USA ) and 42 psi ( Eur) . Difference between reference- and maxcold- pressure,is used to highen up reference for higher speed then 160km/99m/h, and for camber angle above 2 degr( alignment) Maxcold is sometimes for XL// even 60 psi( read of Toyo using it) . An XL tire with 44 psi maxcold is that low, that highening up for speed and camberangle can not be done enaugh. So maxcold pressure has low value, and is introduced for the american market, because law prescibed it. On LT tires mostly only reference- pressure is given , wich only since a few years is also maxcold, the tiremaker allows. Before that often 10 psi extra was prescribed for roadhandling, or 75mh maxspeed for ST tires.

 

[JLTD]

Originally Posted by CapriRacer

Originally Posted by JLTD

Originally Posted by CapriRacer

... First, tire wear is relatively insensitive to inflation pressure. Within a few psi of any value, the wear will be about the same.

Huh?? With all due respect you are dead wrong here. Chronically underinflated tires WILL wear both outside edges. Chronically overinflated tires will wear the center.

Sorry, but I spent 15 years in tire research and 15 years in field testing of tires. One of the things looked at was trying to get tires to be insensitive to irregular wear. I think where we disagree is over 2 items: 1) How much affect does steering vs drive position have on wear. It's a lot more than you might think. 2) How much pressure is "chronic"? If you are talking 15 psi, then I'll cut you some slack. But that's the kind of level I documented for steer vs drive. Let me give you another example. On many FWD cars, the specified inflation pressure is the same front to rear, in spite of the fact that there is a HUGE weight difference front to rear - yet, there isn't a huge problem with the center wearing on the rear tires (one in proportion to the amount of overinflation.) That's what I mean by insensitive. And in all fairness, the rear tires of a FWD tend to develop irregular wear (some incorrectly call this cupping wear.), but it is driven mostly by alignment - toe, in particular - with inflation pressure aggravating the situation, not being the driver.

I agree heartily that alignment and driving habits are the largest components of wear. Absolutely. My comment was directed solely towards inflation pressures. I do not have any exact numbers or research, only personal experience.

 

[CR94]

Originally Posted by JLTD

... Chronically overinflated tires will wear the center.

Maybe with bias-ply tires. I've "chronically overinflated" radial tires for over 800k total miles on multiple cars, and have NEVER seen one wear thinnest in the center.

 

[jadatis]

Originally Posted by CR94

Originally Posted by JLTD

... Chronically overinflated tires will wear the center.

Maybe with bias-ply tires. I've "chronically overinflated" radial tires for over 800k total miles on multiple cars, and have NEVER seen one wear thinnest in the center.

The same with underinflation. A radial tire wears evenly within a large range. So you can go verry low in pressure only for wear. But sooner with to low pressure for the weight and speed, the tire overheats,, and damages ireversible, after that , even when filled up, every cicle the begining crackes , crack a bit further, and mayby only after 3 years , damage is that build up, that tire blows. Then still evenly weared tires. Even a to narrow rimm for the tirewidth, can give centre wear, wich then can not be solved with changing pressure.And the other way around for to wide rimm, as is done with staggered tires for tuning reasons. But we are wondering off a bit from the original question. But topicstarter needs to give more data before I can calculate pressures for him( or her?).