[Padgett]

OK you do not have to use the maximum inflation. What you do need to us is an inflation appropriate to the use. In the upper ranges the inflation vs load is pretty linear so if you figure a 2720SL is about 4k running down the road and the tongue weight is 450 than the residual is 3550 adding a 15% shock factor and you are back to 4080 or 2040 per tire. If the tire is rated at 2830@ 80 psi then the theory says 57 psi so 60 is fine.

OTOH my 205x75R15 LRD are rated at 2150@65 psi so using the same method you get 61 psi or about 4 psi more than the 225s mainly from the lesser chamber volume.

All you really need to know without getting into complex math, standing wave effects, & tire engineering is that load is related to volume and psi. The tire size (205/75) relates to volume. The main thing is that higher "Load Ranges" for a given size add is more psi. Also radials have less drag (run cooler) than bias ply.

I use a similar method when racing in stock classes but figure the entire vehicle load is on the outside wheels in a hard corner (1+ gee) which produced some astounding pressures. All I can say is that when first using this method I began hitting inside pylons.