what are they thinking - Grand Design

JamesBr wrote:
Given that I have yet to see a 5th wheel yet that can balence 100% of its weight on the axles only, I fail to see why you need tires rated above GAWR to be safe. The weight on the axles transfers to the weight on the tires.

If I follow your train of thought all trailers are overweight unless they axles can carry 100% of the GVWR no matter what size the trailer is. Even if the trailer is long enough that there is less then a 1% chance the axles will take on the full weight of the trailer.

The reason why tires should be rated as high as they can is because the ST tires are the weakest link .
When the ST and LT scale ratings were implemented the threshold of the tests was set to a lower standard for ST than the LT rating .
For this reason ST tires are actually UPRATED as to the sidewall weight capacity .
A similar size Goodyear ST tire is placarded for 3450 # while the similar sized LT tire is placarded for 3042 # .
The reason to increase the tire weight rating in an ST tire is because it is UPRATED for weight placard without being more tire .
Plus it is cheap and easy at replacement time to build in a safety margin by going to a higher rated ST tire or an equivalent weight rating in an LT rated tire .
The ST tire scale assumes the trailer sits most of the time .
The LT tire scale assumes the truck move most of the time .
The reports of ST tire failures are about 20 times more prevalent than truck tire failures on this forum .