135 bounces per minute on the highway

[LONGHAIR]

Originally Posted by K10-Kansas

Do MT 35’s bounce like that just because?

"Just because" ....No.
Even though they haven't been legal here for decades, I have personally run 40" mud tires for thousands of miles. They do not have to be abusive.
Back then, especially with those big bias-ply tires, actual roundness was the biggest factor. Some were so bad that balancing was very difficult. Truing was the solution.
Radials are generally better, in that aspect, but it's not absolute.
Even if they don't shake the truck, truing them can make a big difference.
It is hurtful to see how much rubber can sometimes need to be removed, during the truing process, but it really does extend their life.
Smoother rolling tires reduce the load on the suspension/shocks, which are trying to control them.
The springs are doing the lion's share of the work. Shocks are really only dampening the action.
I would take them to a place that can dynamically balance them. It can tell you a lot. If they are out of round, they can tell that too.
Finding a place to do the truing, might be a challenge though.