Tire fitment question

[mbulriss]

Has anyone replaced their 12R22.5 tires with the new 315/80R22.5 tires on a 90's
era wide body coach with the fiberglass fenders? Preferably a 91 coach. Are
there any clearance problems on the front when turning, or when at rest and
aired down?

The reason I ask is because the 315s are a full 1.1" wider than the 12Rs and I
barely have room to get my hand between the front fiberglass fenders and the
12Rs when the air is down. For people trying to learn about Birds, because of
that, you make sure your front tires are pointed straight ahead when dropping
the air suspension.

Also, what about the clearance between the drive axle duals with the 315s? They
call for a minimum dual spacing of 13.8" versus 13.2" for the 12Rs on there now.

Finally, I note that all the Michelin sites seem to say check with them if you
have 8.25" rims, which is what we have on the widebody 90s era Birds. Is there
a problem there? They list both 9.0 and 8.25 as approved rims, so why the need
to check with them?

On the plus side, the 315s come in Load Range L, which is a very nice step up
from the 12Rs which are Load Range H. So you go from 6780 lbs. max load per
single to a whopping 9090 lbs. max load per tire on the singles. That's very
attractive on the fronts especially. Even more of a plus, the 315s are about
$60 less per tire but about $16 more on FET, so they are each still about $44
cheaper when you net it out.

Thanks for any input folks.

Mike Bulriss
1991 WB40 "Texas Minivan"
San Antonio, TX