The June 95 issue of Grassroots Motorsports says this:
"While we're on the subject of handling, if you're still running the
155/80-13 tires that came with the car, get rid of them. Even if you don't
go to offset rear springs or lo9nger studs, you can snugly fit 175/70-13s on
your stock rims without serious rubbling problems. The difference is
If you do modify the suspension, think about a nice set of alloy wheels
to allow even wider rubber for your car. These wheels are much lighter than
stock. Vega GT wheels fit the Spridget and can be found in most any
junkyard. You can pick up a nice set of Minilite replicas new for about
Total Tuning for the Classic Midget and Sprite by Daniel Stapleton has a
whole chapter on wheels and tires.
"A final point on wheel choice relevant to the square arched Spridget is
that it can be impossible to fit certain wide wheel/tire combinations without
flaring the arch, so be warned. The practical tire size limit is 165/70 on
standard rims and less if the aftermarket wheel dishes out to any extent
greater that the standard wheel."
" The subject of tires is a big one and, of course, I've only used a
small number of combinations on my own car. There are some things always
worth knowing: do always use the same tire widths front and rear as unequal
widths give some undesirable, if not dangerous, handling characteristics such
as sudden understeer/oversteer. Don't try to fit low profile tires to wire
wheels - they are not designed for them."
There's a lot more about tires, but you question really was about
wheels. The only other thing I recall reading was about oversize wheels and
tires increasing the unsprung weight an actually having a negative effect on
the handling. My guess from what I've read so far is that a set of Minilite
replicas would be the way to go. Call Seven Enterprises (don't have the
number handy) or Mini Mania (800-946-2642) for advice since both deal in
modifying Spridgets more than some of the other vendors. Mini Mania often
has discontinued or used items available.