OK, I am going out on a limb here. I am wondering is anyone has ever changed from 19.5” wheels to 22.5” wheels on a class "A"?
I have 6 lug 19.5” rims and see that there are 22.5” rims that have 6 lugs also. As I line up my spare wheel and the 22.5" rim, they seem to be compatable. I have checked to see if I have enough room as far as diameter for the new tires as far as wheel openings front and rear. I have also checked to see if the larger tires would hit the frame on cornering and there is plenty of clearance there also on the front.
I have Dana 80 axles on my coach and at present with the tires that are on there they are rated at 6340 FF and 12000 RR. I have checked on other Dana 80 axles and see that they will go as high as 10,000 FF and 25,000 RR.
I am looking for more capacity from the bigger tires and of course, it would drop my RPM significantly at highway speeds. I am looking to get the engine revs to more manageable and back into my torque range, especially at sustained periods of time.
SO, has anyone made the switch from 19.5” rims to 22.5” rims?
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1997 Veri Lite RL1200 on a '02, K3500, CC, DRW, 8.1L, Allison, 4.1 gears, Bridgestone 225/70R19.5 tires.
One observation and maybe I'm missing something, but I have noticed that all the complaints about the Workhorse chassis handling are on the units with 22.5 inch wheels. When they went to the larger wheels, I don't know what other changes were made, but just am observing when the complaints about handling appeared. Makes me wonder if the added height had anything to do with the handling problems. Different shocks seemed to correct the problem, so if that is the source of the issue it can be fixed, but something to consider.
all the complaints about the Workhorse chassis handling are on the units with 22.5 inch wheels
Workhorse had a shock issue, but the uninformed will take the above quote and run with it.
One issue you will have is additional unsprung weight with the heavier wheels. I would look into a higher load range 19.5 first and for your rpm range there are a couple of overdrive add ons available. try this link US Gear
Tell us what kind and size of RV you have. Also what engine then everyone can give you better answers as to the wheels.
Maybe going to larger wheels puts your engine under the sweet spot when cruising on the freeway. Hard to tell unless more info.
John and Cindy and Misty Rain and Senor Paco(Chihuahuas)
1994 Coachmen Catalina 300 MB RD
in sunny Clyde, Calif. KE6IDM
Doc, in general you don't want to do this. The taller tires affect not only engine rpm, which in the case of most class As will hurt performance significantly, but also affect braking adversely. Putting larger diameter tires on will not increase GVW - and when you consider the effect on brakes - should actually decrease it. If you need more tire capacity in order to reach axle or chassis capacity look for tires with a higher weight class in the same diameter. If you need different gearing to best use the engine you've got, change gearing.
You mentioned clearance but what about when you hit a bump in the road and the shocks and springs bottom out. Will the tire bottom out on some part of the coach first? Travel for the suspension system is usually designed for the original tire size and much larger will cause problems. If you start this project it could end up costing quite a bit more with all the little things you discover as time goes on.
I should have included that I have a 1990 Suncrest SunBus that is 34’ long and it has a 460 Ford EFI with a C-6 and pulling a 5.12:1 gear. I am sitting on an Oshkosh MC-FG frame that has full-length rails. The “sweet spot” is supposed to be 2500 to 2750 RPM. I have 14.75” hydraulic brakes that are used on Ford trucks that are up to 12,000# F and 26,000# R axles. So I should have plenty of brakes.
In doing some investigating, I have been aware of the Shock issue with WH.
If I was to go with an overdrive unit, I don’t think that I would use US Gear, as they have a habit of getting caught in between gears on the shifts. I would have to install a Gear-Vender if I were to go that route. However, I already have a need for tires, and that is a normal expense, and an overdrive would be at least a $3000.00 extra expense. Plus the issue of finding tires while on the road is also something that I am looking at.
As for the higher load range 19.5” tires, I have not had that much luck in finding any “G” or “H” rated tires, and even then I would only gain at most an inch on the taller diameter. AND finding these tires on the road is also harder than just “F” range.
The only thing that I have not been able to ascertain, for certain is how much jounce is in the suspension. I know that I have checked distance between the jounce stop rubbers and frame and where the top of the tires would be with the bottom of the wheel-wells. There seems to be enough clearance at those points. Actually the wheel opening trims on the rear would have to be modified at the bottom to allow the tires to be installed without any problems.
I had a 2003 Suncruiser 33V on a W20 chassis with 19.5" wheels. In 2003 Winnebago offered the 35U floorplan on a W20 or W22 chassis, however, they both were 19.5" rims. The only fdifference betwen the two was the tires. To achieve the 22K GVW the 19.5" tires went from load range F up to load range G, thus increasing the capacity of the coach. Presently they now offer 22.5" rims on the W22 chassis. They also change the rear axle ratio to compensate for the extra tire RPMS and loss of power. The other thing is that the 19.5" chassis had a spare tire tucked up between the frame rails, but the 22.5" tires wouldn't fit so you got no spare.
My biggest concern (other than the excessive revs, lack of power, and speedometer calibration issues) would be getting the bigger tires to fit. You have to have enough room in the fenderwells to allow for jounce and rebound, rather than just having enough clearance when sitting there. Plus, the bigger tires may hit the frame rails when you crank the steering over hard (again, it could be worse if you bounce while turning).
I'd rather go up one load range to give you the extra capacity and skip all of the other hassles.
2007 Allegro Bus 42QRP - Cummins 400 ISL
2012 Jeep Wrangler Rubicon Unlimited