Air pressure jumping in front tires

Too much increase on front tires... under inflated and too much weight on the front. What size tires?

Another thought is that you adjust the tag axle to remove some weight from the front axle. I adjust mine so that the drive tires run at 95 psig and the front at 105 psig. Those pressures are 5 psig above what was calculated by axle wt. The fact that you need 117 in the front and only 85 in the rear suggests you have a lot of wiggle room in moving some weight rearward.

I agree-- first suspect (since we don't know actual weights) and tires is that the fronts are under-inflated.

A 28 PSI rise in fronts vs half that for the drives strongly suggests under-inflation leading to over-flexing leading to more temperature rise.

Another observation: If 117 is "under-inflated" (and likely near PSI needed to carry maximum rated load), then would sure see if the next size/load range tire would fit.

On edit:

Please post what tires (brand, model and size) you have.

If you have the wheel position weights (better) or axle weights, and GAWR (from plaque near driver's area) please post those as well

I think this is very normal. Many different things can affect the temps around the tires including simple stuff like where the muffler pipes are located, if there is a bit more weight on one side (braking). They can even be affected by which side of the coach the sun is on as they are black rubber and absorb heat.

Going from 117 psi to 147 psi front means at an ambiënt temp of 65 degr F an inside tire temp of 185 degr F , wich is way to hot.
Hottest peace of rubber can be over 270 degr F then at wich it hardens and damages .Best is to keep inside tire temp below 130 degr F. And better make your goal inside tire temp of 115 degr F when driving about 55m/h.
This needs higher cold pressure.

My tires are set at 120 all the way around. Usually, while driving, my tires run 135-138 except the Tags, they are much lower.

My front and rear tire pressures will increase 10 to 14 PSI depending on the road surface temp. This is according to my TPMS.

Have you had the coach weighed recently to insure that the tires are properly inflated for the load? Usually tires will get hotter quicker if they are under-inflated for the load.

I would say yes, with qualification. My tags go up about like yours do, but the fronts do not go quite that high. They will go up proportionally to the beginning pressure if the temps are the same, however, and the fronts start out higher so the will expand more on a proportion basis I would think. My fronts get up in the 132-135 range or so usually. Hope this may help, Happy Trails Bert