unsprung mass is everything below the springs... axles, brakes, wheels, tires, etc...

 

When installing wheels and tires that are larger than stock, unsprung mass comes into play because your brakes are designed to be stopping a mass that is the size that the factory put on it. Putting taller, wider, and heavier tires and wheels on your truck will negatively impact your braking capability, due to the rotating tire and wheel having more leverage over your brakes than originally designed for. Going from 265/70/17 to 285/70/17, not a big deal. Going from our size tires to one that's 35" tall and 15" wide, with what's probably 100+ lbs. of wheel in the middle of it, is probably going to make a noticeable difference. Also, your shocks, and springs to an extent, are there to dampen bumps and such in the road. Having to control a wheel and tire combo that is probably close to twice the original weight is going to be hard on parts. Something I've not seen mentioned, but was wondering about though. If these are 300k mile tires, they must have the wear properties of cast iron. On a semi I'm sure it's fine, but on a truck as light as ours compared to a semi, what would that do for your traction? I would think it'd be like a hog on ice when it rained or tried to get slippery otherwise.

 

the ride is rough as heck w/ those things, even aired WAY down... don't get me wrong, they look KILLER

but I wouldn't put them on anything I used for anything besides showing off

Forrest

 

Alas, I've either decided to go with the 19.5's, or a htt htb2