CapriRacer wrote:
CapriRacer wrote:
Opps, I may have made a mistake. I'll get back when I have it figured out.
I'm back and, yup! I made a mistake - and it has to do with the topic at hand - ST tires vs LT tires.
I went to the Tire and Association Yearbook and listed all the ST tires by size and Load Range - many more than what is available on the market. I then went in the same book and looked up LT tires with the same "size" (meaning the 3 dimensions) and the same Load Range, and compared the load carrying capacities.
Just an FYI, there are mucho, many more LT tires listed in the standards manual than are available in the marketplace. So while there is very little overlap between ST's and LT's that are available for purchase, there is a much better link between these 2 types of tires in the standards manual.
The result? For the same "size" and Load Range, an ST tire carries between 9% and 15% more load than a comparable LT. For the purposes of simplicity, I am going to call this 12%. This is close enough for our purposes.
So using the 12% value in the earlier example, a change from an ST225/75R15 LR D to an LT225/75R16 LR E, the increase in load carrying capacity is 18%, not the figure I quoted earlier.
Sorry for the error.
This is exactly the information I would like to put in a chart. For all of the LTs that are readily available in the marketplace with a tread appropriate for trailer use (FastEagle would be a big help in coming up with a good list), find out what the load rating is of an ST tire of the same size (even if not available in the marketplace).
Just doing a quick calculation here -- 1.09 x 3042 = 3315 (rounded down to the nearest pound). At 12% that would be 1.12 x 3042 = 3407 pounds. At 13% 1.13 x 3042 = 3437. So it might be that an LT235/75R16 LRE is a direct replacement for a ST235/80R16 LRE (Goodyear Marathon 3420 lb) if the ST235/75R16 LRE is 13% or more than the LT235/75R16 LRE. But it wouldn't be a replacement for the Towmax that FastEagle uses which is 3520 pounds. That is why having accurate numbers here would help.
CapriRacer -- can we work up a chart?
