moving from 225R75/16 to 235R85/16 PROBLEMS

HiTech wrote:

pianotuna wrote:
Hi McZippie,

Thanks for finding the link and posting it. I've placed my order, and am having it drop shipped to the tire dealer.

HiTech,

The 235 tires can carry 300 lbs more than the 225 at the same tire pressure on Duals.

Next order of business is Toyo or Michelin.

Excellent but verify wheel load as well if changing wheels. My Alcoas were listed for e350 but I got the ratings in writing from them to ensure they would work on a fully loaded E450 as well.

Jim

I don't know the wheel load specs but they look the same as the Ford OEM rims.

Here's a link to my thread that measures the dually spacing:
235 Dually Spacing.

pianotuna wrote:
Hi McZippie,

Thanks for finding the link and posting it. I've placed my order, and am having it drop shipped to the tire dealer.

HiTech,

The 235 tires can carry 300 lbs more than the 225 at the same tire pressure on Duals.

Next order of business is Toyo or Michelin.

Excellent but verify wheel load as well if changing wheels. My Alcoas were listed for e350 but I got the ratings in writing from them to ensure they would work on a fully loaded E450 as well.

Jim

In my case, Southwest Wheel sold the very same rim (steel) for my 03 f-250 that Ford used as OEM.

Don,

The 235/85R16 tire should be excellent for you if you get that gap spacing big enough between the two rear duals ... it will definitely provide you with an extra margin of safety and reliability versus load. It looks like MrZippie has done it right with his rim switch.

I just checked details at the Michelin site and it looks like they're phasing out the MS tire with just a very few sizes left in the MS, and 235/85R16 is not one of them. If you go with Michelin, your only choice will be the MS2 tire and it is indeed Green X rated in 235/85R16 size ... with a 70,000 mile tread warranty too.

You will have an outstanding 16 inch rim Class C setup if you change to this tire and the new 16 inch rims to go with it. Let us know how it works out for you!

Hi McZippie,

Thanks for finding the link and posting it. I've placed my order, and am having it drop shipped to the tire dealer.

HiTech,

The 235 tires can carry 300 lbs more than the 225 at the same tire pressure on Duals.

Next order of business is Toyo or Michelin.

Very good I suspected someone still made alternate offset wheels. Do need to verify the load they can handle though.

Jim

Below is a link for Ford E350/450 16" x 6" dual wheels with 5.35" offset 8-6.5" bolt circle built for LT235 tire. I run them on our rig with 235/85/16 tires. No spacers needed!

http://www.southwestwheel.com/store/p-1841-29578.aspx

Well ... the Chevy/Ford vans that many U.S. motorhome builders start with were probably originally designed for multiple curbside and/or small warehouse delivery dock pickups and drop-offs. As such, being low to the ground made for speed and convenience - and small diameter tires/wheels facilitated this.

If owners can put up with the higher step-ups to get into them, I see some advantages to taller tires on typical Class C rigs. Larger diameter tires take road bumps smoother, ofttimes have higher higher load ratings for improved safety and wearability margins, get a bit better tread mileage due to less frequent rotational contact with the surface, and - last but not least - provide better chassis and body clearance for mild offroad use.

After all, pickup trucks with their campers in their beds often have taller, more rugged tires on them than what comes stock on Class C motorhomes. IMHO, it makes a lot of sense to "upgrade" Class C tires/wheels from what comes on them stock. A Class C motorhome has requirements different from a typical commercial van's requirement for ease in making curbside cargo transfers.

pianotuna wrote:
Hi,



#3 give up and use the OEM size.

What would you do?

Why do you want to change what the engineers have calculated best for your vehicle? What is to be gained by changing tire size?

You asked what I would do. I would stop trying to outsmart the engineers who designed and built my vehicle.

When I bought my seven 215/85R16 MS2 tires in the summer of 2011 Michelin gave that tire and size a "Green X" rating. At the time their 225/75R16 MS tire that had been around so long and was stock on so many cutaway vans did not carry this Green X rating.

Further studies indicate I may be wrong on the reason for the Michelin Green X Energy Saver rating being mostly due to the 215/85R16 MS2's slightly narrower tread width. Many factors contribute to lower tire rolling resistance and the 215/85R16 MS2's Green X rating may have been mostly due to the change in materials in Michelin's fairly new (at the time) MS2 design. Here's one link to help explain rolling resistance (note also that overall tire diameter also is a factor):

http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=175

The Michelin 215/85R16 MS2 tire also had/has a higher mileage warranty rating of 70,000 miles. My stock Michelin 225/75R16 MS tires had a 60,000 mile warranty. Even though most folks will never have their RV tires on for anywhere near this many miles, what this longer warranty means is that for any particular mileage tread wear should be less than that of a 60,000 mile tire.

Note that a slightly narrower tread area tire presses down on the road surface with increased pounds per square inch with any given vehicle weight. This can provide better adhesion/traction under some conditions ... but also the negative of less float on extremely soft surfaces.

I'm also "hoping beyond hope" that the new sidewall materials used in Michelin's MS2 tires partially or fully solves the problem that Michelin IMHO has regarding too-early sidewall deteriation.