I could write in this thread all day and not penetrate the numerous fallacies that have already been posted. So, I’ll just post a few specific observations.
Tire testing: It is a subject that comes up in a long tire thread.
Manufacturers of tires suitable for use on our highways must first accomplish the necessary conditions to achieve permission to display the DOT symbol/acronym on their tires. That will require a series of tests approved by the DOT. That does not mean the DOT will oversee the testing. Initially the tires will be tested by their manufacturer. When they determine their tires are good enough to pass all testing standards they will use a third party testing facility (approved by the DOT). Only a percentage of the final production run will be tested. The paperwork is then submitted to the DOT for approval. Once approved the tires are shipped to wholesalers/retailers for distribution.
The ST tire is, as its name implies, special. Therefore, its DOT approved testing criteria will be tailored to its designed function (s). The ST tire is not designed for the drive or steer axles. It does not have to provide the construction necessary for those positions. The ST tire is just designed to withstand heavier loads than comparably sized tires from other designs.
The best example of the load capacity disparity between the ST tire and a like sized LT tire is quite an eye opener to those that are not very familiar with the various tire designs. The ST235/85R16E has a 3640# load capacity at 80 psi. The LT235/85R16E has a load capacity 3042# at 80 psi. Most often the LT tire will be heavier in weight than the like sized ST tire. That extra weight will most often be in the form of added items - taller treads, extra steel belt, sidewall inserts, etc. - that provide durability which does not add strength.
ST tires are speed restricted to 65 MPH. What does that mean? At 65 MPH it’s providing 100% of it’s load capacity.
Speed ratings are set by the tire’s manufacturer. There is a highly touted LT tire that has a 99 MPH rating when used on it’s designed market and a 75 MPH rating when used on self propelled RVs.
Already too long. Maybe more later.
FastEagle
