I know this thread is about tires. Another thing to think about while using leveling jacks long term is that, depending on how they are installed on your Class A, they may increase its effective wheelbase by up to 60 inches causing additional deflection to the frame. Deflection is a 4th power equation meaning that the deflection increases proportionally to the 4th power of the wheelbase in inches. I once saw a Class A MH similar to mine except with a slide ('99 Southwind Storm 30H @ 178") and a 208" wheelbase. Major difference, . . . aftermarket leveling jacks. The owner stated he was currently experiencing his 3rd windshield pop out and water leaks were always a problem, but never with mine. His jacks were installed on the frame in front of the front axle and behind the rear axle leaf springs. On newer passenger cars, the fixed glass is a structural member but on Class A MH's to my knowledge, its not. Yes, . . . frames do flex, coaches prefer NOT!
deflection for a simply supported beam = 5wl^4/384EI
w = lbs. per lineal inch
l = length in inches (wheelbase)
E = modulus of elasticity for steel = +-30,000,000
I = Moment of inertia for beam section (varies with girder section and gauge)
This is not exact rocked science but close enough for RV work.
Chum lee
