Re: Wheel offset?

[Scott Fisher <sefisher@domain.elided>]

Bill Magoffin asks:

> Anybody know if  7" wide 14" wheels will fit under the rear end
> of a '65 105 Coupe (Lower arches) and if so what offset?. 

I suspect not, at least not without some attention to the bodywork. 
I've got 14 x 6 rims on a '67 105 coupe, wearing 185-70 tires, and I
have heard the occasional rub from back there -- usually when I'm
four-up in the car.  There are scuff marks on both the inner sidewalls
and the outers, so there are clearance problems both with the inner lip
on the fender and with the inboard fender wall (up against the rear
seat).

The qualifying factor is that I've got stock ride height and stock
springs.  If you use stiffer springs, you may not get as much body roll,
which may assist in using the larger wheels/tires; on the other hand, if
you drop the car, you'll be closer to the problem (so to speak).

You can see the tires and wheels closely in the picture at the top of
this URL:

http://www.living-history.org/classics/serpent/wheels.html

Black on black doesn't always scan well, but fortunately I'd just put
someshiny stuff on 'em and you can see the outermost tread block to get
an idea of how they fill up the wheel wells.

> The front does not seem to present a problem. 195/60 tyres 
> (Tires) to be fitted.

I snagged a front tire once on the fender lip -- trying to make a U-turn
(uh, that's a U turn to the left in this country :-) assisted by a
driveway with a steep ramp.  Just went out and checked: it's the right
front fender, at about 2:00.  I'm trying to remember the events that led
up to it, but it was basically full-lock steering, a fully laden (two
adults, two children, and their weekend luggage) car, and the added
compression from going up a driveway ramp while already heeled well over
during a U-turn.  

If I were planning to fit larger wheels/t[i,y]res on this car, I'd at
least roll the inner fender lips to provide some clearance there, then
see about reducing the backspacing at the rear to give a slightly wider
track and hope that the reduction of interference from that rear fender
"shelf" was enough.  And who knows, when I get the 2-liter in I may need
more rubber...

One final topic on tire width: Sixties-vintage cars have a certain
"feel" to them with their relatively narrow tires that is, well, fairly
special.  Fitting wider, modern rubber certainly improves grip -- and if
you're building a time-trial or track day car, there's no question that
it's the right choice.  But I've noticed, when I've installed wider,
60-series rubber on vintage cars, that some of the responsiveness,
liveliness, and the sense of traveling "on rails" goes numb with modern
tires.

So if you're just looking for a pleasant driver, give some thought to
keeping relatively narrow (by modern high-performance standards) rubber,
in an appropriately aggressive competition-oriented compound.  That'll
give you the grip you're looking for with the "feel" of the vintage car,
though at a cost in tire life.

Just something to keep in mind -- and you're in a far better place than
I am to decide what you want, given your intended use for the car.  

 --Scott

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