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Re: MGB tire size comment

To: british-cars@autox.team.net, gougar@csd4.csd.uwm.edu
Subject: Re: MGB tire size comment
From: sfisher@megatest.com (Scott Fisher)
Date: Wed, 27 Apr 1994 17:21:08 +0800
~    I have seen it mentioned here several times that it is not possible 
~ to mount tires larger than 185 on an MGB without modifications to the
~ fenders or at least a method to restrain lateral axle movement in the
~ rear. 

Possible?  Anything's possible. :-)  What I've seen, in the half-dozen
or so MGBs that I have been connected with, is that some 195s rub at the 
rear, and most 185s rub on "later" MGBs.  I've got 185-60s on 14 x 5.5" 
rims on The Green Car, which is a March '71 tourer.  The first MGB I had 
was a '74, and 185-70s (mounted on stock Rostyles) rubbed on that car.  
Other MGBs I've seen, worked on, or with whose owners I've commiserated 
over one thing and another, have fallen largely but not unequivocally 
into these two camps.  For example, TeriAnn's '68 MGB-GT rubbed when she
put the 195s on it, but Andy Banta's '67 BGT doesn't rub even with
205s.  Go figure.

Now, there are several other possibilities.  For starters, not all
tires have the same shape, even for the same "size."  The curvature
changes from maker to maker; on all the rubbing I've seen, it's been
the sidewall, not the tread, that rubs. 

Also, TeriAnn is using 15" rims, while Andy is using 14" Rostyles.
That itself could cause problems.  Who knows...

~ My 1973 BGT has a bazillion (well, 130000) miles on the rear springs,
~ so they are SACKED, and I mounted 195/60 - 14's on the back and 185/60 -
~ 14's on the front with no clearance problems whatsoever. 

Well, of course, you won't have a problem with the fronts; they have
the full-round wheel arch that gives lots of clearance, especially
with the 185-60 which has a smaller circumference than the stock tire.

On the back?  I think maybe you're just lucky. :-)  My '74 rubbed, and
we had to bang the lip up inside the fender.  It didn't show from the
outside, and the rubbing was really minor, but it did rub.  That was with
185-70 tires, so maybe the curvature of those tires -- or the curves as
I mounted them on the Rostyle wheels, perhaps -- interfered.

~ Is this
~ because I am running 60 series tires? It seems that I have the 'worst'
~ combination for tire clearance: chrome bumper car with low ride height,
~ sacked out springs, rotten spring pads that allow a LOT of axle movement.

In this case, axle movement is your friend: think about it.  Inside of
the car jacks up as the car rolls; outside of the car droops way down;
then the body of the car moves laterally outboard, giving clearance 
to the tight space (the outside wheel) while the inside wheel has lots
of air above it due to the roll.  (And yes, MGBs do roll that much,
especially with sacked out springs.  For a real scare, watch someone
autocrossing a stock-suspended MGB sometime.  Yeesh...)

~ But I haven't had a tire so much as touch a fender.

That's unique, for the 195s.  I also haven't had a problem at the rear
with my '71 and the 185s, which is why I usually recommend them as a
safe bet; you can be pretty certain that 185-60 won't rub, and if you
go wider, that certainty diminishes.  



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