I purchased my car with Michelin XZX 165-R13 (NLA) on stock rims and
they worked just fine (plenty of clearance) unless you really wanted
GRIP (they squealed nice though). I then switched to 13X5.5" rims and
managed to get a set of 185/60-13 Bridgestone RE71R tires. These tires
are fantastic. They grip like crazy (they should since they are a
roadracing compound with a treadwear rating of 50) and really perform
well in the wet. These tires are very difficult to obtain now as
vintage sprite racers love them for wet track tires and they have been
out of production for a couple of years.
13X5.5 rims and 185/60 tires will fit on most square arched cars with a
little bit of work. I think that setting up for this size of tire is
the best choice if changing to wider rims. This setup allows for use of
a large number of performance tires on a Sprite (Yokohamas, Sumitomos,
BFG, and others). The 175/60 and 175/70 size are less common but still
have a couple of choices left. The 175 section tires will work better
with a 5" rim while the 185 section tire really needs a 5.5" for more
optimal performance. The 175 section tires will probably require
slightly less work to fit than most 185's. All tires vary by
manufacturer, meaning that one manufacturer's 185 tire may actually be
~5mm + or - than another manufacturer's 185 tire.
1) You need to fit bigger diameter (stock studs break with modern
radial tires) and longer wheel studs (if fitting alloy rims). The stock
3/8" studs are a joke if you are looking to get a serious amount more
grip. Be safe and keep those wheels on your car.
2) You will most likely need a wide variety of wheel spacers in 1/4" to
1/8" and maybe 1/16" increments. It is likely that the rear will
require a slightly different amount of spacing from side to side for an
optimal setup. This is normal.
3) The rear springs must be in decent shape. If they are not, offset
springs may make your life easier and may allow use of up to 205 section
tires (with additional modifications at both the front and rear),
however this is a costly way to go. New stock rear springs with 2
leaves removed for 1/4 elliptic cars seems to be the way to go. 1/2
elliptic cars could use stiffer springs than stock and lowering blocks
from what I have seen.
4) A well mounted panhard rod or watts link is a MUST. Even with
delrin bushings all around the rear moves far too much without it.
5) The lip of the rear fender can use some grinding. Maybe a 1/4" or
less. One of the little binding brackets on the 1/4 elliptic springs
may also need a small amount of relief. Remember to repaint the ground
sections or they will start to rust.
6) Carefully take a jack and a piece of wood and use it to slowly push
the fender from the inside out. I actually used a floor jack in a
contorted position for this. Be careful, do it slowly, otherwise you
WILL crack paint. It does not take that much movement in the fenders to
fit this size of tire.
7) Install the tires, take a good look, and make sure that nothing is
touching. Take the car for a ride down a nearby BUMPY, TWISTY road and
listen. If you need to do more work, you WILL hear it. If you hears
rubbing/grinding, slow down, do whatever it takes to minimize the
rubbing as you are driving, and get home. When you get back home, pull
off the rear wheels and look for polished areas in the rear or areas
with black ground tire residue and work on those sections. Repeat until
no rubbing.
8) The front may grind in low speed parking lot types of maneouvres,
this is not a problem. You will almost never get close to full lock
when at speed. Just use spacers to move the rims away from the steering
components without getting them outside of the bodywork (some rims may
require grinding the steering ball joint slightly, but this is minor)
and everything will work just fine.
The clearance with this setup is amazingly small without rubbing and the
fender work is unnoticeable unless on a show quality straight car
(typically straighter than came from the factory). Anyway, this is
probably beyond what was asked about tire sizes. Mike Gigante was a
great help in convincing me that this was not as difficult as it sounds.
I hope this is useful to someone thinking about this mod.
Jackson Zimmermann
jzimmerm@albemarle.org
'64 Sprite (1/4 elliptic, disk brakes, side curtains, 1275 & 5-speed =
quick fun)
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