19.5 rims versus 22.5

[Hikerdogs]

Originally Posted by Betr2Trvl

I don't know why, but I keep coming back to this thread......

Think about this question this way. How can you compare the ride quality between these Toyotas - A 2000 Toyota Corolla, a 2012 Toyota Camry, and a 2016 Lexus LS, and say that the differences are solely due to the wheel / tire size? Can't be done, anymore than most of the other comparisons made here between one MH and another.

As noted, one person has changed the wheel / tires from 19.5 to 22.5 on thier MH. And to no surprise, not only does it ride smoother (as much do do with being able to run substantially lower air pressures with the larger tire size, as it does with rolling diameter) it impacts shift points, gas mileage etc. since you are changing the overall rolling diameter which impacts effecting gearing of the drive train. It also puts a higher load on the transmission which may be an issue down the road; my bet is CJ7ole has significantly different axle ratios in his jeep with 35" tires than it had stock with wheels / tires with a much smaller rolling diameter (or, he is replacing his clutch once a year).

As I noted previously, as well as a couple others - in short, the wheel / tire sizes chosen by the manufactures is simply part of the overall design of the chassis given its intended use. And, with that a bigger, heavier MH which happens to be on larger wheels / tires is probably going to have a smoother ride vs. a lighter MH which happens to be on the smaller wheels / tires.

Your tire pressures have to be properly set too. While most people focus on tire pressures related to thier load ratings, it is the spring effect of tire pressures that impact your ride quality. Yes, the larger rolling diameter smooths out pot holes too........

I put the heavier 24k chassis on my coach vs. the standard 22k, so with that, I have a very high CCC for a gas coach. Since I weighed the coach and confirmed I am running nowhere near my max load, I was able to significantly reduce my tire pressures since I am essentially "over sprung" on the chassis vs. my running weight. And, to no surprise, my ride became significantly softer, so much so, that within a few miles after resetting the tire pressures, my wife commented how much smoother and quiter the MH was, not even thinking about the fact that I had changed the tire pressures.


Regards

As far as I can tell the subject of 19.5" wheels and tires as opposed to 22.5" wheels and tires is specific relatively new gas engine motorhomes. I am not aware of any DP's currently in production that use the smaller wheels and tires.

Looking at the 2014 F53 Brochure all chassis use the same engine and transmission regardless of tire size. The major difference seems to be that the lower GVWR chassis (16,000 lb. and 18,000 lb.) have a 4:30-1 differential ratio, the mid range GVWR chassis (20,500 lb. and 22,000 lb.) use a 5.38-1 differential ratio, and the heaviest GVWR chassis (24,000 lb. and 26,000 lb.) have a 6.17-1 differential ratio.
http://www.fleet.ford.com/resources/...2014_LoRes.pdf

Given this information I doubt there would be appreciable difference in longevity or performance of the transmission or engine. I would expect lower fuel mileage in the larger chassis given the higher differential gear ratios and the added weight

The 19.5" wheels are standard on the 16,000 lb. , 18,000 lb. and 20500 lb. chassis, even though the 2 lighter chassis come with a 4.30 differential ration and the heavier one comes with a 5.38 differential ratio. In addition they all come with the same size and load range tires.

The 22,000 lb. chassis comes standard with 22.5" wheels and tires, with an option being the same size 19.5" wheels and tires standard on the lighter chassis.

The 24,000 lb. and 26,000 lb. chassis come with the same wheels as those that are standard on the 22,000 lb. chassis with larger (255/80R 22.5G BSW (14PR) Highway Metric Radial Tubeless tires) as opposed to the (235/80R 22.5G BSW (14PR) (Standard) Highway Tires) on the 22,000 lb. chassis.

[Betr2Trvl]

Originally Posted by Hikerdogs

As far as I can tell the subject of 19.5" wheels and tires as opposed to 22.5" wheels and tires is specific relatively new gas engine motorhomes. I am not aware of any DP's currently in production that use the smaller wheels and tires.

Looking at the 2014 F53 Brochure all chassis use the same engine and transmission regardless of tire size. The major difference seems to be that the lower GVWR chassis (16,000 lb. and 18,000 lb.) have a 4:30-1 differential ratio, the mid range GVWR chassis (20,500 lb. and 22,000 lb.) use a 5.38-1 differential ratio, and the heaviest GVWR chassis (24,000 lb. and 26,000 lb.) have a 6.17-1 differential ratio.
http://www.fleet.ford.com/resources/...2014_LoRes.pdf

Given this information I doubt there would be appreciable difference in longevity or performance of the transmission or engine. I would expect lower fuel mileage in the larger chassis given the higher differential gear ratios and the added weight

The 19.5" wheels are standard on the 16,000 lb. , 18,000 lb. and 20500 lb. chassis, even though the 2 lighter chassis come with a 4.30 differential ration and the heavier one comes with a 5.38 differential ratio. In addition they all come with the same size and load range tires.

The 22,000 lb. chassis comes standard with 22.5" wheels and tires, with an option being the same size 19.5" wheels and tires standard on the lighter chassis.

The 24,000 lb. and 26,000 lb. chassis come with the same wheels as those that are standard on the 22,000 lb. chassis with larger (255/80R 22.5G BSW (14PR) Highway Metric Radial Tubeless tires) as opposed to the (235/80R 22.5G BSW (14PR) (Standard) Highway Tires) on the 22,000 lb. chassis.

What I think you are referencing from my previous post is the paragraph regarding the guy that put a 22.5' wheel set up on a coach that came with a 19.5" set up, and the ramifications of that change; not factory set ups. Sorry if that was not clear.

Given what you posted on factory wheel / tire set ups, it supports exactly what I was saying (or trying to say ).

Regards

[NC25T]

Originally Posted by Betr2Trvl

A Honda Fit would ride smoother on the wheels and tires from a Mercedes 550 too...... it simply does not need them to function as intended. Just like a smaller MH does not need 22.5" wheels to function as intended either.......

Not true.... Adding wheels/tires that probably weigh 50-75 lbs per corner would make the fit ride and handle like complete crap

[Betr2Trvl]

Originally Posted by NC25T

Not true.... Adding wheels/tires that probably weigh 50-75 lbs per corner would make the fit ride and handle like complete crap

You mean compared to how a Fit rides and handles anyway? . I am sure you really understand the exaggerated point I was trying to make....... overkill is overkill, and bigger tires within reason would make it ride smoother, but it is simply not necessary given the design parameters of the car. You want a smoother riding Honda, get an Accord.

[NC25T]

Yea... Lol... and I know you were throwing sarcasm out there as well

Small cars the driver can feel a lb or so of additional unstrung weigh, I would think in a RV it would be more like 10lbs or so could be noticed, possibly more.