Originally Posted by palmetto rogue
Tireman, your concerns over shear puzzle me. G614s are LT tires as are the tires on my 2500 pickup. Only difference is G rated vs E rated. The truck mfg recommends 60 front 75 rear with 80 psi max on sidewall. Why is there no concern about shear on the front tires of my truck. It seems to me the frequency of shear forces is much greater on the truck than the trailer.
Ya I understand your confusion
But the reality is that when computer analysis is used to look at the internal structural loading, the fact that tow vehicle tires are all operating at very low "slip angle" (difference between travel direction and angle the tires are pointed to) is significantly lower than for tires on a trailer.
The reason for this is that the center line of of tire rotation for the TV tires points to the center of the radius while the trailer tires, especially on tandem axle trailers, does not.
This translates into a higher slip angle which means higher internal structural twisting forces on the belts. The computer model suggests 24% higher on the TT tires than TV tires even if all tires were the same with identical vertical load and inflation.
TV front tires have "Ackermann
" alignment designed into the suspension but TT have no allowance other than bending of tires, springs, spring mounts and bushings but the forces to bend the springs etc have to go through the belts of the tires.
This is a MAJOR reason for TT tire life to be much shorter than Motorhome or TV tire life.
Hope this helps.