China Tire Manufacturing

FastEagle wrote:
This topic is way off track and needs to be closed. It's just turning into another LT/ST thing and that was not my intent.

FastEagle

Before the moderators do that, allow me to clear up some misconceptions.

First, the tire manufacturers through The Tire and Rim Association (TRA) are the ones who set up the relationship between load and inflation pressure - and that includes the notes about changes needed to run ST tires at speeds greater than 65 mph (that Kumho quoted).

The vehicle manufacturer (and this applies to trailer manufacturers as well as car and truck manufacturers) take the TRA tables and use them to specify the inflation pressure needed for THEIR vehicle. The tire manufacturer doesn't know what vehicle their tires are going on, so they are in no position to recommend anything other than what the vehicle manufacturer specifies (I'll come back to the point in a moment.)

The information about what the vehicle manufacturer specifies for tires is written on a sticker, commonly called the vehicle tire placard. It lists the original tire size and the specified pressure for that size.

It's hard to tell, but it seems that most (and maybe all) trailer manufacturers intend their vehicles to be limited to 65 mph, because without exception, they specify the maximum pressure listed on the sidewall of the ST tires. I say this with a bit of trepidation as I can't possibly know what EVERY trailer manufacturer does. I can only state that I know of no exceptions.

One of the issues in the ST vs LT debate that seems to get lost is that trailers are generally run at or near their GVW's and GAWR's. This is just not true for cars and trucks, which are frequently run empty. That means ST tires are more highly stressed for longer than their counter parts. (Please note: I am excluding LT tires mounted on trailers in that last statement.)

I also want to point out that there are side to side and front to rear load variations on tires. This is frequently ignored when people weigh their trailers (or their cars and truck, for that matter.) It is important to remember that the WORST case is what causes tires to fail - not the average. You MUST account for this variation in your calculations - or you aren't looking at the picture properly.

Now back to a point I left hanging:

People frequently point to the load tables published by the tire manufacturer to determine inflation pressures.

First, these tables are DIRECTLY taken from The Tire and Rim Association. There is NO difference between tire manufacturers.

Second, it is important to note that these tables are the MINIMUM pressure to carry the load specified in the table. It has never been stated as a recommendation.

Third, for those who have used the tables to determine their inflation pressure: Did you do the calculation to see what the vehicle manufacturer did for the fully loaded situation? I thought not. If you do, you will likely find that the inflation pressure specified is HIGHER than the minimum - and sometimes substantially higher than the minimum. You should do the same.