moving from 225R75/16 to 235R85/16 PROBLEMS
Hi, More problems have reared their heads. The E-450 has a different rear axle, than the F-450. The F-450 will allow up to a 245 width with no change of rim size for the rear duals. The E-450...
Forum Discussion
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.
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.
