There seems to be a lot of questions about fitting tires on various
Spridgets. In my search for the same answer, here are some things that I
have heard from multiple sources combined with my experiences.
Aftermarket Rims: 13X5 is the preferred rim size for fitting on Spridgets,
some 13X5.5 will fit (thin casting is needed with a correct inset), however
they will be very, very close on square body cars and WILL require a panhard
rod and some judicious fender work with a jack and a 2X4 and maybe even
offset springs. The rim size will be a determining factor in fitting tires.
A 185 series tire prefers 5.5" or wider, however 5" rims still yield good
results and are within the manufacturers specifications. 205 series tires
are not recommended for any Spridgets unless the fenders are box flared and
rims are 6" or wider. Getting rims that fit properly are the key to fitting
larger size tires on Spridgets, inset can be taken out with spacers and long
studs, however offset is a PITA. Go with larger studs, as the stock studs
break with stock tires and rims. This is required before moving to
wider/stickier tires. Studs are a very serious safety issue!
Tire Sizes: The optimal tire size for the hard driving lot without flares
is the 175/70-13 or a 175/60-13 on a 13X5 rim. The width of the tire and
rim combination makes a very fine package. The 175/70 used to be a very
common size and was available in almost every competition compound. Right
now the closest thing is a 175/60 (4% smaller than the stock 145 tires)
however only Yokohama makes this particular size in a DOT competition tire
any longer. The A032R which is new with very nice wet and dry grip but
reduced tread life and the A008RS which was recently discontinued and was a
fantastic tire with decent dry grip (equivalent to shaved high performance
street tires), marginal in the wet, and would last forever (seriously, my
'85 BMW 535i has been to more than 25 driving schools on a set of A008RS
205/60-16 and they still have decent tread and grip). If you can find a set
of A008RS tires, I would suggest them unless you plan on driving in the rain
regularly (I have an new set in storage). Continental makes the CH90 in the
175/70-13 size, I have no experience with that tire although Tire Rack lists
them as a high performance tire.
Fitting Various Tires: If you are running 1/4 elliptic springs and want to
got with 165 in width, expect to rebuild your rear suspension with poly or
Delrin bushings (square body cars will need it, RWA cars may not). If you
will be going with 175 or wider you will need wider rims than stock
(actually 165 tires could use wider rims as well, but may fit on stock
rims), I would say that it is a must to install a panhard rod and use poly
bushings if you will be doing any spirited driving. Later 1/2 elliptic
springs may not need the panhard rod with 175 width tires if you have poly
bushings installed and do some fender work (I'm just passing on what I've
heard about this since I've only owned a 1/4 elliptic car). It is possible
to install 185 width tires on 5" or 5.5" rims on some square body cars (not
all) without flaring the fenders and without offset springs, however a
panhard rod WILL be necessary (I use the Winner's Circle one) and you will
have to do some work with an angle grinder on the fender lip and some
judicious fender work with a bottle jack and a 2X4. This is the way to
maximize the tire potential of the Spridget and still stay stock looking.
The tire availability in the 185/60-13 range is far wider than any other
size that Spridget owners can potentially fit under a stock body and is very
nearly the same circumference.
So in summary, the 185/60-13 size offers the most choices with the newest
compounds and tread patterns, but takes quite a bit more work to fit. The
175/70-13 or 175/60-13 is the best size for 13X5 rims, but has very limited
offerings (although the A032R is a good choice) and these offerings may
disappear in the next few years as demand wanes. Narrower DOT approved
tires in the 145/155/165 range have little performance value as they are
geared toward economy cars. YMMV as my views are definitely geared to the
performance and autox spectrum!
Jackson Zimmermann
jzimmerm@albemarle.org
'64 A-H Sprite
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