Tire inflation

allen8106 wrote:
I have a similar situation. I have a 5ver the weighs in at 10,500 unhooked. Now I haven't yet weighed the axles or the truck axles. I just upgraded from GY Marathons with a D rating to Maxxis with an E rating. My problem is that the aluminum wheel is supposedly only rated for 65 PSI yet the tires are rated for up to 80 cold. I just completed a 2000 mile round trip to Mesa, AZ and ran the tires a 65 PSI cold. I have a TPMS and observed that the tire pressure grew from the 65 cold to as much as 80 PSI running down the road on a day where the ambient air temp was 65 degrees.

Going from 65 cold to 80 warm means a pressure rising of 23% wich makes the inside tire temp to be warm about 165 degr F , wich is to warm, Normal rising only by driving is about 10% pressure rising so warm inside of about 110 to 115 degr F.
This means that your E rated tires are deflecting to much.

A stiffer tire ( E-load stiffer then D-load) needs more pressure for the same load, so if for D-load 65 is enaugh , E loads needs for instance 70 psi.

I would rather risk the rimms leaking by to hing pressure then the tires to fail and blow when driving at speed.
Most likely the 65 psi of the rimms is cold pressure and some rising for warm is calculated in , yust as is done for tires and valves.

Once read a story on Dutch caravantrekker ( traveltrailersite) about rimms leaking when they chanched from P-tire to D-load with using the 65 psi pressure , wich was apperantly to much for the rimms. By the forces on the rimm the rimm went leaking.
But this was for a rimm that was made probably for 35 psi and now used for 65psi.
This is the only case I found, so asume this leaking of the rimm does not happen that soon, there must be a large reserve in that for rimms.

So highen up the pressure until warm is about that 10% higher then cold, and your tires are save.
Risk is that you have damaged your tires already by the to low pressure and so the tire will blow when filled to 80 psi.
then the high pressure is not the blame but the to low pressure before.

Best is to calculate it with my made spreadsheet , or let me do it.