Different Tire Issue (I think)

BFL13 wrote:
Phil, if you use "taller" tires than originals, it reduces the pulling power.

That doesn't apply to the tires on a towable. Bigger diameter tires on tow trailers and 5th wheels makes for each portion of the tread contacting the road surface less and for each section of the sidewall to bend less. Less tread contact per mile reduces tread wear per mile and reduces heat from tread flexing per mile. Less bending of each section of sidewall per mile reduces heat from the sidewall material flexing per mile. Both of these effects together add up to less heating of the entire tire per revolution.

Regarding taller drive tires on self-powered RV's ("motorhomes"), of course with a lot of tire diameter increase over stock one would need to use a lower gear to achieve the same pulling power on grades or when wanting to maintain acceleration at any given rate. However, all the time while this is going on less heat is being generated within the tire material due to the lesser revolutions of larger diameter tires.

For our particular small motorhome on it's overkill chassis - the lower rear differential ratio (over the normally used chassis) delivers all the needed pulling power even with larger diameter drive tires. Due to the differential's gearing, I don't need to use lower transmission gears for pulling power or better acceleraton even though the tires are taller.

If we were using a towable RV, I wouldn't use taller tires on the tow vehicle. I'd only use taller tires on the trailer or 5th wheel to reduce the danger of their tires failing from excessive heat generation mile after mile - especially blowouts, which are very dangerous on a trailer or 5th wheel.