The pictures should tell the story. Space-saver spare tire from SAABs pre-87 fit the MGA and MGB perfectly. This makes for a lot more room in the boot too! Cost at local salvage yard $11.

The problem is a little different for a wire wheel car, as it would be difficult to find very narrow wire wheel with compatible splined hub. But original MGA 48 spoke wire wheels are only 4" wide, so this is more a problem of overall tire size.

At 10:38 PM 5/22/06, Jim Ferguson wrote:
>"To solve some space and fit problems with the 165sr15 spare, I got a space saver compact tire mounted on the wire wheel rim. It is for "limp-home, repair" only. I would not use it in the West where a repair was more than 25 miles away. (I don't want to damage my differential.). The tire dealer said the old tube was ok since it was ONLY for very temporary use at low speed and very limited distance. The tire used was a T125/70-15. The overall diameter was reduced about 4" and the width 1.5". The top folds better and more space in the trunk."

A word or warning here about the tube. It is definitely taboo to use an oversize inner tube. If the tube has a fold or wrinkle it will rub and chafe on itself and will fail with only a short amount of driving. Click for larger picture. An antique tire dealer may have a tube small enough for this application, as some older cars used much smaller tires.

Another possibility could be to seal the spoke holes in the rim and run this one tubeless. The original 48 spoke wheels are not too difficult to seal, as all of the spokes go along one edge of the rim in the bead area of the wheel.

The difference in tire diameter should not bother the differential significantly for a short run. The 15% difference in tire diameter, makes the smaller tire turn less than two revolutions per second faster than the larger one at 50 MPH. As long as you are not running at higher speed or towing a heavy trailer or climbing steep mountain roads, this should not overheat or wear out the differential. Of course it is not recommended to make a habit of running long miles with the small tire. Most space safer tires are rated for 50 miles at 50 MPH, and may have 3000 miles total tread life expectancy.

There is another approach for welding a splined center hub from a wire wheel into the center of a modern space saver (bolt-on) steel wheel.
See: www.chicagolandmgclub.com/techtips/mgb/ss_spare.html
Since the srandard 48-spoke wire wheel rim is only 4" wide, this appears to be more an issue of the tire size than the wheel. I don't know if it gets much smaller than the space saver spare on the wire wheel shown above. So perhaps the welded hub may not be worth the effort (or cost).

On 06 March 2017, Brian Paddon in the UK wrote:
"I have purchased a Volvo V40 wheel and tyre off Ebay. Fitted it today. Works fine and is 600mm o/a diameter which matches my alloy wheel/tyre combination".

On 08 March 2017, Brian Paddon wrote:
"The wheel hub is marked 6-02 Netherlands, Rim 2.5 ET40, 3.50Bx15H2. The tyre which came with it is a Continental T125/90R15 96M, which is approx. 600mm o/a diameter which matches the 186/65R 15 road tyres. I believe the wheel is off a 1995-2004 Volvo sport? Yes it fits and spins with no problems over the front caliper".

Addendum August 25, 2021:
While the Volvo space saver wheel does have the correct bolt pattern, the center hole is too small to fit over the MGA front wheel hub. The wheel does not go on far enough to even get the lug nuts started on the studs.

Standard steel wheel on front hub (left). Volvo space saver wheel on front hub (right).

However, it does apparently fit on the rear. So if you have a flat on the front, you can move the good tire from the rear to the front, and install the Volve space saver wheel on the rear. Then you will want to take it easy on the highway, because there will be two revolutions per second difference between left and right side wheels at 50 MPH, and you don't want to overheat the oil in the differential.

See next page for Twin Cam/Deluxe space saver spare.