jadatis

Link's went a bit strange, but about tirepressure they write next. The basic rule is that all tires on the same axle are set to the same pressure, based on the heaviest side. And this does not state that its unsafe to use different pressures, only that the basic rule is to set the same pressure on the axle.

I only wrote that it might not be unsafe to have different pressures, yust my opinion, so cant show you confirmation of that. I could ask the same question to KirkW, if he could show a link that writes its unsafe. But your friend who does my dually idea for 40 years, what are his experiënces with it. Does he have tmps, and does he notice less pressure rising of inner tires. And does he experiënce different roadhandling? And in my spreadsheet for calculating tirepressure for motorhomes, I calculate one pressure for the axle. In part 3, where you can give axle-end weights, I make the average percentage of the loadcapacity belonging to the calculated pressure 90%, but if heavyest side goes above 95%, it calculates for that 95% using, and then lightest side goes under 85% used, a border I determined to give bad comfort. Then the heavyest side still has some reserve for things like, inacurate reading of pressure, and weight, pressure loss in time, etc. Lower then 100% used of loadcapacity for the pressure, gives higher pressure as outcome. To high pressure is never bad for the tires, but to low pressure can give overheating, so that must never happen. Can lead to tirefailure, and even accidents.

I dont know if its unsafe to have different tire- pressures on the same axles, but every car or tiremaker prescribes it that way. My idea is for dualload-axle to give the outer tires a bit higher cold pressure then the inner tires. 5psi max, and inner tires as prescribed or calculated for the load. Inner tires heat up more because of roadcurve more deflected, and worse cooling, because on inner side. Then warm pressure about the same. And better weightdivision between inner and outer tire, because outer tires lift up the inner tire a bit. Same effect as a tag-axle, if more suspension pressure on tag, more weight shifts to tag and front axle, and less weight on Drive axle. Tag system devides front rear direction, Dualload 5 psi higher devides sideward direction.

Needed tirepressure is all to give the tire a deflection that wont overheat any part of tirematerial, when driving the speed for wich it is determined. So for that Load on tire, and max speed used( wich you wont go over for even a minute) is important. Maxload of tire is calculated by tiremaker for reference-speed (mostly 75mpg for your tire) and - pressure ( that 120 psi). But for lower weight on tire you can use lower pressure. Vehicle maker uses GAWR's for that and simply devide by 2 or 4, with no reserve mostly. I determined that using 90% of loadcapacity per axle given, for 99mph, gives maximum reserve with still acceptable comfort and gripp. Reserve is needed for next. Unequall weight R/L on the axle, always on RV. Pressure loss in time. Inacurate reading of pressure and load. Etc, etc. Can make a list for your tire, with my determined reserves and given per axle, so you dont need to devide by 2 or 4 or add reserves yourselves. Need tire-specifications for that. Made spreadsheet for that, in wich I use my own extra safe formula, even saver then used for official lists. Can also put in other or no reserves, yust write how you want it.