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Old 11-20-2017, 08:09 PM   #28
MattE303
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Quote:
Originally Posted by CWtheMan View Post
This is basically what the industry standard says about replacement tires. If they are the same basic size the tire placard is still correct. However, with a higher load range you have the option of adding inflation pressure to gain load capacity reserves above the LRE tire. By the same I mean something like a ST235/80R16E that provides a maximum of 3520# at 80 PSI. The ST235/80R16G will provide the same amount as the LRE when inflated to 80 PSI.

Plus sizing is another upgrade and the one that gives most people trouble. The same standards applie. The replacement tire must provide (via inflation) a load capacity equal to, or greater than, what the OE tire provided at the recommended inflation pressure found on the tire placard. Because inflation charts will not work with any other sized tire, NHTSA has approved the use of an auxiliary tire placard. The information used to set the recommended inflation pressure for the plus sized tire and the tire size need to be displayed on the auxiliary tire placard (home made). It should be placed adjacent to the original - unobstructed - tire placard. A savvy retail tire installer will do that and also make a note in the vehicle owner's manual. (Reference provided via PM on request).

Most will ask, why is recommended tire inflation pressure necessary? Because the entire automotive industry in the USA revolves around the need to know what the safe pressure is. Many that have trucking experience get confused. That's because that industry operates under a completely different governing body, the Federal Motor Carrier Safety Association, FMCSA. They do not have recommended inflation pressures. They inflate to the load carried - minimum. But, a tire is a tire and their tires cannot be inflated beyond their maximum load capacity.
great info, thanks CW!
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