Dual tire pressures?

[rpatnaude1]

how do i determine correct dual tire pressures for a 91 fourwind class c?

[mel s]

Originally Posted by rpatnaude1

how do i determine correct dual tire pressures for a 91 fourwind class c?

rpatnaude1
Weigh your coach and use the inflation pressure shown on the tire manufacturers inflation chart for the tires used on your coach.

[ga traveler]

Weighting is the best. If you lightly load your coach as I do, and you know it is not over loaded, you can go by the sticker in the motorhome that has the tire pressure on it.

[youracman]

What mel s said.

I recently had mine weighed with the MH loaded as we usually load it for travel.....full fuel, 1/2 tank water, empty holding tanks, etc. Used a truck stop ($10) and got front and rear axle weights. Using the mfr's (Bridgestone) tables online it turns out that I can lower my duals to from 80 psi to 70 psi if I want cuz I am way under the GAWR for the rears. The name plate on my rig says 60 front and 80 rear......this is fits right in on the Bridgestone chart for my GAWRs.....so the MH mfr planned on me driving at some time with the MH loaded to the max allowables .....bumping up against the front and rear GAWR's (I suspect all MH mfr's do that.....for good reason.)

I like to put tool boxes. bottled water, and other dense "stuff" in my toad....just to stay well under my max allowables on the MH itself..... I believe lots of folks with limited cargo carrying capacity (mine is only about a "measly" 1000 lbs on the placard) do the "load the toad" trick. Fortunately, I have lots of reserve where the GCWR is concerned.

Safe travels.................

[rpatnaude1]

I put 4" valve extenders on all 6 of my class C tires prior to my 1400 mile trip from Maine to Florida . when I got to FL my rear dual extenders were missing. Is it possible that they vibrated off?

[Old Crows]

Yes, it is very likely the 'extenders' worked their way off. The solution is to install metal valve stems like Dually Valves. They will stay on and also make it easier to check your tire pressures.

All four of the 'rear' tires should have the same pressure.

There is a yellow and black placard on the driver's door sill. It will state the tire sizes; the Gross Vehicle Weight Rating (GVWR); the F & R axle ratings, AND the F & R tire pressures for the F & R tires at MAX GROSS VEHICLE WEIGHT RATING.

While it's important to know the weight of your RV to assure you are not over MAX, 98% of the effort in determining tire pressure has been done for you. If you are at, or near GVWR, use that number. If you are under, you may be able to squeek by with a little less. Like a PSI or two or three.

A third number is stamped on the tire. That is the MAX COLD INFLATION PRESSURE FOR THE TIRE to get the max carrying capacity of the tire. You don't want to use that. Use the placard data.

Example: Our View Profile placard says 61/61. The tires are max 85 psi. I use 61. Actually, somewhere around 61 depending.... usually about 58, 59, 60, 61 because I'm about 700 lbs under the GVWR when all up for a trip.

And know that a tire will increase in pressure ~1 PSI for every 10 degrees F. So if you set it at 60 when it's 50F, once on the road the tire heats up and let's say you are somewhere about 95F ambient and a hot road. Your tire temp might be 110F. Your pressure will increase by about 3.5 psi after its been in use for a short time. So you are up to about 66 psi ... or more.


Keep it simple. They've done the work for you.

[rpatnaude1]

1 more q uestion for now... 1991 fourwind c. Anybody know sizes (gal) are in my tanks... Black, grey, fresh and gas? My sensors alyways indicate at least 3-4 full

[Kiawah]

I put 4" valve extenders on all 6 of my class C tires prior to my 1400 mile trip from Maine to Florida . when I got to FL my rear dual extenders were missing. Is it possible that they vibrated off?

I would doubt it. If they started to loosen, they would leak air, and you would notice the flat. It's also highly unlikely that 'both' would work their way loose.

I suspect somebody parked next to you and saw those brand new shiny extenders and decided to help themselves to them.

[ga traveler]

Originally Posted by Kiawah

I would doubt it. If they started to loosen, they would leak air, and you would notice the flat. It's also highly unlikely that 'both' would work their way loose.

I suspect somebody parked next to you and saw those brand new shiny extenders and decided to help themselves to them.

I agree with Kiawah. I installed dozens and dozens of extenders. Never had one come off. a few came loose and caused flats (That is why I have dually valves on my coach) Someone along your route has a brand new set of extenders. They did NOT find them alongside the road.

[wa8yxm]

Originally Posted by mel s

rpatnaude1
Weigh your coach and use the inflation pressure shown on the tire manufacturers inflation chart for the tires used on your coach.

I will second that and add two comments
You need 4 corner weights, not just "Total" or "axle"

Second: the easy way (There is a small cost but as I recall it was well under 50 bucks) is to go to RVSEF - RV Weighing & Safety Education and find the weight links. Make an appointment, they come to you with portable scales (Same kind "Diesel Smokeys" use by the way, option 2 is to make friends...)

But when you call them have your Tire make and model and size (IE: Mitchlin XRV 22.5 x whatever it says on the side of my tire)

THey come out with a chart, They check your tire pressure gauge to see how good it is.. They weigh your RV and make some suggestions. and tell you how much to blow (up the tire that is).

NOTE: some folks insist all tires on a give axle must be same pressure.... I AM NOT AMONG THEM and believe the two ends may be different if the load is different.

The concept is all tires the same DIAMETER.