Tire Pressure?

[mikemc53]

2022 Gulfstream Conquest 6280 on a Ford E350 chassis. The tire pressure recommended on the driver door tag says 75 psi front and 65 psi rear (drw). Last year I had a young tire tech tell me that they should all be at 80 psi, which I thought might be a bit high.

I run about 80-85% weight capacity and I was wondering if the door tag is accurate. The reason I ask is that the door tags are likely put on before the vehicle is modified to become a motorhome. Would that change the recommended tire pressure?

Thanks in advance.

[jadatis]

The change to motorhome wont change the GAWR's. So you would think it wont change the recomended pressure, because calculated for GAWR's, wich you are not allowed to go over.

But now, motorhomes are often overloaded and /or have unequal weight R/L on the axle.
So drive all the time with 100% or more of allowed weight on it.

Together with that most have tires with yust enaugh maximum load to cover the heavyest axle, makes it that they often need more then the maxloadpressure of yours 80 psi, to be safe to laws of nature.

So determine axleloads, or better axle-end loads acurate by weighing fully loaded as going on tripp, and give tire specifications, and I can calculate a pressure with maximum reserve, but still acceptable comfort and gripp for that.

[Golden_HVAC]

Ford put the same sticker on every E-350 they produce, and they know it will be put into a RV chassis, and should be close to the maximum GVWR. So if Ford says 65 PSI, that will give the most comfortable ride. 80 PSI and it will feel more bumps in the road. The tires should last 7 years - and you normally do not wear them out in that time.

You really should not keep the tires once they are 7 years old.

Fred.

[bobndot]

mikemc53, you said your rig is an E350 and you run it at 80-85% weight capacity ? That 350’s gvwr is 12,500 At 80-85% capacity you would be at 10,000-10,625 ? For a 30 ft class C, that seems very light to me.

[12th_Man_Fan]

What the door tag says is for gross weight. Until you have weighed it that is what you need to go with in my opinion.

[rjstractor]

They must have figured out how to build them lighter- I had a 1998 Gulfstream 30 foot C with no slides that ran about 13,700 loaded and 12K empty, on an E450 chassis. Having said that, those tire pressures are as recommended by Ford for a fully loaded vehicle. No reason to go any higher unless you are overloaded.

[bobndot]

Being that a 6280 30’ non- slide has a gvwr of 12,500, i would think being careful packing it , you run it at or near gvwr. As said , look at that weight/psi chart.

[Grit_dog]

^What he said.
Without knowing what size tires are on it and how loaded down it is, none of us can say.
The tire kid may be right. And he’s certainly not grossly incorrect for the front axle. Unless you’re somehow loaded @ss heavy, 80psi on pizza cutters up front is ok.
Rear, same thing, although at 12.5k gvwr you’re probably 7500 +\- on the rears. 65 psi would be the minimum except in hot weather/high speed high duty cycle I’d want to be wired up more.
Or if you’re running in real cold weather and/or snow I’d want to be a tad on the low side of “perfect” for traction purposes.
That said 80psi isn’t grossly over pressure in the rears for that rig unless it’s basically empty. And even then it won’t hurt a thing or tire wear. Just ride a little more harsh.

[enblethen]

first thing you need to do is weigh the rig ready for the road. Gear on board, fresh water and the like.
Then go to the tire manufacturer website and get the inflation chart.
Inflate the tires according to that.
I run five pounds over chart indicated pressure!

[Second_Chance]

On what was the "young tire tech" basing his recommendations - the max PSI on the side of the tire for load range E tires? The folks who built your RV know more about the requirements than would this young tire tech. Are you seeing any signs of underinflation? If it were me, and in the absence of abnormal wear, I'd stick with the door sticker.

Rob