Another tire pressure post - :)

[jd4010]

I am replacing my Goodyear RST G614 tires with the identical product. On the old tires I ran 110 PSI religiously. Did a CAT scale weigh and the trailer axles came in at 12240 lbs with most everything in the RV except a fridge full of food and some clothes. We do not haul with any tanks full. I am thinking that when loaded, it probably bringa us to 13k.

Goodyear inflation charts say that on the G614s 110 psi allows for 3750 lbs of weight so at 4 tires, that would place me at 15k. At 95 psi allows for 3415 lbs of weight so at 4 tires, that would provide me a capacity of 13660 lbs or about 1400lbs above my CAT weight hence some margin.

I would love to reduce the inflation to 95 to give the RV less of a rougher ride. But for all my years, I've been one to follow the sticker on the vehicle for tire inflations. Looking for thoughts from those that adjust based on load not the sticker.

 

[Mike134]

Was the treadwear uniform across the tire indicating correct pressures? "Reading" your old tires will give a much better answer than anything we throw at the wall here.

 

[llr2800]

I generally favor the load charts, however since you are that close I would stay at max.

My main reason is your 4 tires are probably not sharing the load evenly. If you got individual wheel weights and they are all very close lower may be ok, or whatever the chart says for the heaviest wheel.

 

[jd4010]

Was the treadwear uniform across the tire indicating correct pressures? "Reading" your old tires will give a much better answer than anything we throw at the wall here.

Unfortunately I really cannot go by the old tire wear. We had negative camber issues that were causing inside wear on opposing axle sides (meaning right front wear and back left wear). I just got done installing new Dexter axles, equalizers, etc and now replacing the tires since a) the old had more wear on the inside and b) tires were 5 Y/O anyway. I worked with Dexter to identify the issue sending them photos, lots of measurements, etc. Everything seemed in check so we believe the issue was with bent spindles or the axle tubes themselves.

But prior to the camber issue, tires were wearing evenly. So to your point, maybe best to keep it at my old pressures.

 

[jd4010]

I generally favor the load charts, however since you are that close I would stay at max.

My main reason is your 4 tires are probably not sharing the load evenly. If you got individual wheel weights and they are all very close lower may be ok, or whatever the chart says for the heaviest wheel.

There is no doubt that the tires are not sharing the load evenly. The largest slide holds the full fridge, stove, oven, pantry, TV, fireplace whereas the opposing slide has the table, 4 dining chairs and the 2 recliners.

Appreciate the input. Thinking I will stick with the higher pressures.

 

[Chuck_S]

There is little reason to play the Tire Pressure Game.

Placard tire pressure will handle the GVWR of the vehicle. The manufacturers prudently post that pressure to avoid the danger of under inflation which overloads the tires and causes blow-outs. Passenger cars usually run "pretty close" (a scientific term) to GVWR so that pressure is fine. Vehicles which have very high GVWRs compared to their actual weights and tire capacities can run lower pressures. Roll the dice.

ST (special trailer) tires are designed to run at maximum sidewall pressure but only if you're using the tires that were factory fitted. In this case placard and sidewall pressures will (should) match. If the Load Range on the tires as the vehicle came from the factory is "Good" -- and it is! -- thinking that a higher capacity tire is "Better" is false. Stick to the placard, sidewall pressure is too high and the trailer will get pounded to death. Run placard pressure even with those needlessly overrated tires.

-- Chuck

 

[jadatis]

Found your exact given maxload and pressure in Goodyear pdf, for 235/85 R 16 3750 lbs AT 110 psi.
Is an LT tire, and I think RST given is to sugest its ST, so users dont ask questions about why LT on TT and not ST.
Its yust allowed LT, and you are better off with LT on TT to laws of nature. More hounest giving maxload for max 99mph calculated, that you dont drive that does not matter, gives even more reserve to prevent overheated tires.

Also in that pdf the ST version in 235/85R16 4400 lbs AT 110 psi, but is for max speed 65mph.


But then the total tandem weight of 13000 lbs. It is a traveltrailer with 10% to 15% on tonge? So total then probably 14300 to 14950 lbs, what is your GVWR?


Tandemweight given, you must add a reserve first.
Better would be axles weighed, better even axle-end weight, but tandem weighed is better then no weighing at all, and dangerously estimating.

I can make you a cold pressure/ axleloadcapacity list with build in maximum reserve, but still acceptable " comfort" for the trailer.

So give if you want per axle, tandem, can give both in one list.
Then made with a formula that leads to even higher pressures then the official used in Europe for all kind of tires, and since 2006 also in US for P-tires.
Then in the end it could lead to 110 psi advice, but mayby still lower.

Edit: changed the story a bit, because reading back I saw TT and tandem weighed. So if some strange sentences its because of that.

 

[jadatis]

Reading back, I also saw that I have all the needed info to make the list.
And because of the build in maximum reserve, you dont need to do pre- or after-calculations yourselfes. 12925 lbs gives 105 psi, so I would not bother lowering 110 psi will do fine, and lower only gives less, absolutely needed, reserve.

Tandemload/cold psi/ axleload
4695 lbs/ 35 psi / 2347 lbs
5300 lbs/ 40 psi / 2650 lbs
5901 lbs/ 45 psi / 2950 lbs
6499 lbs/ 50 psi / 3249 lbs
7094 lbs/ 55 psi / 3547 lbs
7686 lbs/ 60 psi / 3843 lbs
8276 lbs/ 65 psi / 4138 lbs
8864 lbs/ 70 psi / 4432 lbs
9449 lbs/ 75 psi / 4724 lbs
10033 lbs/ 80 psi / 5016 lbs
10615 lbs/ 85 psi / 5307 lbs
11195 lbs/ 90 psi / 5597 lbs
11773 lbs/ 95 psi / 5886 lbs
12350 lbs/ 100 psi / 6175 lbs
12925 lbs/ 105 psi / 6462 lbs
13500 lbs/ 110 psi / 6750 lbs/referencepress
14072 lbs/ 115 psi / 7036 lbs
14644 lbs/ 120 psi / 7322 lbs
15214 lbs/ 125 psi / 7607 lbs