Another tire question

wstalker · 01-05-2017, 08:25 AM

I am looking to replace my tires and would like to go with Toyo. My issue is my Winnebago Vectra 40 AD has 275/80R/22.5 inch Michelin tires and it looks like Toyo has 295/80R/225 tires available. They do not have the size on my motorhome. Is this a possible fit. Do I contact Winnebago to find out?

LJowdy · 01-05-2017, 10:32 AM

The new tire will be 2 inches taller than what you have. You'll suffer fuel mileage and pulling power and maybe they won't clear your wheel arch.
Here's a program to help determine tire sizing: https://tiresize.com/calculator/

NMBluept · 01-05-2017, 12:03 PM

You may want to call Winnebago. Those tires sizes are pretty close (values are in inches):
275/80R22.5: 10.8 wide x 39.8 dia. = 125 circumference, ~508 revs/mile
295/80R22.5: 11.6 wide x 41.1 dia. = 129 circumference, ~492 revs/mile
That's 0.8" width, 1.3" diameter, with only a 4" circumference difference. That circumference difference equates to about 16 revolutions per mile or 3%. Not sure what the accuracy of the speedo is, that's 1.5 mph error at 50 mph. I don't think I could see that error on my speedo. The main concern would be sidewall width and dual spacing on the rear - would tires 0.8" wider (combined 1.6") rub each other when flexed? That's what you need to ask Winnebago or perhaps a tire expert.

BTW tire size calculations are pretty simple:
Convert cross section from millimeters to inches - mm/25.4
Multiply cross section times aspect ratio to get tire height
Multiply tire height times 2 (top + bottom) and add wheel size to get diameter
Example for 275/80R22.5
275/25.4 = 10.8
10.8 x .8 = 8.7
8.7 x 2 = 17.4
17.4 + 22.5 = 39.9
Note there's a bit of rounding here, it gives you an idea of how to quickly get reasonably close values of tire sizes.

skigramp · 01-05-2017, 04:43 PM

Albert ... I am having trouble following your calculation on separation between the duals ... wouldn't .8 inches wider on each tire mean that the tire would be .4 inches wider on each side ... so the space between the two tires would be .8 less? what am I missing?

Stevegd007 · 01-05-2017, 06:21 PM

My two cents. I ask the same question on size & was told the Michelin tire "size" is Unique just to Michelin! Weird I thought! But it does seem this size is only seen on the Michelin brand! I did switch to Toyo's and could not be happier. The fit is just fine. The ride seems better, to me any way. An the cost to my bank account was way less painful. I have no downside to the Toyo tire.

Gary737 · 01-06-2017, 01:30 AM

The 275/80/22.5 Michellin compares with the Toyo 295/75/22.5. The Toyo is about 10mm wider which I feel improves handling and cornering. The diameter and circumference difference are almost identical, and insignificant. Check out Tire Comparison.com and plug in the tire sizes and you can see exact numbers. This swap was recommended to me by Les Schwab for our Itaska 40 ft DP. Now have 5000 miles on the Toyo M177 and happy. As with any, tire pressure is so important.

wstalker · 01-06-2017, 06:28 AM

Thank you for all the feedback. I talked to a fleet tire dealer who basically said the same thing. He said the Michelin tire size is unigue to Michelin, my guess is they feel they can control the market that way. When i asked him about the Toyo tires he said they were practically the same size, but advised me to do my research. I am going to go with the Toyo, just need to find a place to buy them

NMBluept · 01-06-2017, 08:36 AM

You didn't miss anything you caught my error.

Lean 2 · 01-06-2017, 08:40 AM

I'd say those Toyo's most likely will hit your fiberglass fender edges when air bags deflate. I have the Michelin 275's on my 40AD and on one side when fully deflated at rest in my garage that one side is right up against the fiberglass fender inside edge. Just my 2 cents.

Tireman9 · 01-06-2017, 08:43 AM

Quote:

Originally Posted by wstalker

I am looking to replace my tires and would like to go with Toyo. My issue is my Winnebago Vectra 40 AD has 275/80R/22.5 inch Michelin tires and it looks like Toyo has 295/80R/225 tires available. They do not have the size on my motorhome. Is this a possible fit. Do I contact Winnebago to find out?

295 may fit the front but I doubt that they meet the "Minimum Dual Spacing" requirement which is a function of wheel offset.

Gary737 · 01-06-2017, 02:42 PM

So what is the "minimum dual spacing" requirement? I couldn't get an actual number from Freightliner, RV dealer, or otherwise. There is still a large gap for cooling and avoiding contact. Les Schwab tells me I'm safe and good to go.

Also, fender clearance should be easy to see. Just add 5mm to the outside tread and you should be able to see overall picture when deflated, and from my experience that works.

twinboat · 01-06-2017, 04:06 PM

Michelin lists minimum spacing, per tire size, on their website.

You would need to research the brand your buying to find out.

Jim_HiTek · 01-06-2017, 08:11 PM

Tire dealers tried to say the same thing about the 235/80/22.5 Michelin tires on my '02 Winnie, that there was no substitute. I'm really thinking this is pretty much a perpetuated scam. It did take some research but by using the tire scaling app in the following link, I was able to find a competitor's tire that fits fine, would have plenty of space between the rears, and doesn't come close to scraping any wheel wells.

Tire Size Calculator

majfrizz · 01-07-2017, 08:49 AM

One thing I saw on the TOYO tires is that you must inflate to 125PSI to carry the max load of 7160 on each tire. The Michelin you only need 120PSI. and if your rims can only go to 120PSI, that will reduce the load range on tire, this is listed on the TOYO tire charts. something to considered if you are heavy on those tires.

jerichorick · 01-07-2017, 09:49 AM

Quote:

Originally Posted by wstalker

I am looking to replace my tires and would like to go with Toyo. My issue is my Winnebago Vectra 40 AD has 275/80R/22.5 inch Michelin tires and it looks like Toyo has 295/80R/225 tires available. They do not have the size on my motorhome. Is this a possible fit. Do I contact Winnebago to find out?

The Toyo M154 295/75 16 ply (#548230) are working fine on my Meridian. My first trip on them started in OR last June. We traveled to WA, ID, IA (Forest City WIT Rally), TX (Dallas area), AL, GA, MD, MA, LA, deep south TX and now we are near Houston. No problems and the ride is great. Much more comfortable than on the Michelin's. I don't know how they will be as steer tires because I put Continentals on the front. I will never spend that much money again. Long story. They handle great though and should for what I payed.

We had some really heavy rain one day. Not a problem for the coach. Slowed down a bit just to be safe. I usually drive around 65mph when I can.

Happy trails,
Rick Y