Another question from a reader with a "heavy 5th wheel trailer.
Hopefully, this isn’t a duplicate. I tried to post a comment before I saw the email. Thanks for all the excellent information on your site. It is incredibly difficult to determine who is sharing good knowledge on other forums.
I have read through many of your posts about hot tire pressures in particular, but I’m hoping to get your experienced input on a more specific example. How much pressure increase is reasonable in load range H (4805 max load) tires inflated to 122-125 psi CIP? I have tandem axles on a fairly heavy fifth wheel. All weights are within limits (trailer, axle, tires, etc.), but with the wheel-position weights, one of the four tires is carrying c. 4,700 lbs, which is 53% of the total for that axle. I know this violates your ‘85% of max load’ recommendation. However, I’m seeing up to 32-35 psi increases (to about 157-160 psi) after 3-4 hours on the road when in the sun. I have always pulled over for a break at that point, so I don’t know if it would have continued to climb. According to the TPMS, the heavily loaded tire reaches these ranges first, but the other three aren’t far behind; accounting for shade, wind, etc. all four increase in psi and temps together fairly steadily throughout. Generally, the temperatures aren’t much higher than 30 degrees above ambient, but I’m really wondering if there’s a point I should be concerned about the pressure increases. I know it's been said the tires are engineered to handle pressures up to 100% over max CIP, but just trying to find the threshold of when one should begin to be concerned. Once elevated to the point where I pull over to cool things off, I can only get about 30 minutes of drive time before they start touching that 157-160 psi level again. The tires are within specs, but close to the maximum. I can add to the CIP as you recommend, but I’m limited to only a couple of PSI before I hit the max CIP of 125 psi. My rims are rated to 130, but not sure I have the clearance for larger tires, and I’m not sure if I need to consider that. The current tires are Goodyear G114 215/75R17.5. Unfortunately, Goodyear documentation or customer support doesn’t provide much guidance on this.
Any thoughts would be greatly appreciated.