Verified answer

Yeah you can do that, it won't be a problem.

If the steel wheel has a tyre of the same size as the other side then the car will pass - otherwise it will fail. It does not matter whether you have a spare wheel in the boot or not or whether the spare is legal - the spare wheel is not part of the MoT.

Hello

The law states that all tyres including the spare must be road legal. As you correctly point out there is no law that states you must have a spare wheel so you change it but do not put the old one in the car at all. With it in the boot it is a fail, Without it is a pass.

The question comes about the steel wheel and what wheel nuts you are using as they are different for steel ones to the alloy ones?

Normally steel wheels will have normal tyres on and alloys will have Low Profile so check the tyre size, It is written on the side wall of the tyre. If they are the same size on steel and alloy wheel then the Overall Diameter of the wheels will be the same.

You do not say what car you have?

But for example my old Vectra had

Steel rims with 195/65/15 tyres

Normally I would expect

Alloys to be 195/45-50/16 to get the same Overall wheel Diameter.

195 = Width of the tyre in mm

65 = 65% of Width = Depth of tyre in mm (From rim to floor)

15 = Diameter of Rim in inches.

So 195 * (65% * 2) = (126.75 * 2) = 253.5mm So 15 inch + 9.98 inch O/D = 24.98 inches

So 195 * (45% * 2) = ( 87.75 * 2) = 175.5mm So 16 inch + 6.91 inch O/D = 22.91 inches

If 195 * (50%* 2) = ( 97.50 * 2) = 195.0mm So 16 inch + 7.68 inch O/D = 23.68 inches

If 195 * (55% * 2) = (107.25 * 2) = 214.5mm So 16 inch +8.44 inch O/D = 24.44 inches

So I would have to look at tyres of 195/55/16 to minimise the difference on the Speedo?

Andy C

My car does not have a spare tyre, it has one of them tins to fix the puncher and mine has never failed the mot (well touch wood up to press)

http://www.ukmot.com/mot_check.asp says yes you can, the spare isn't part of the test.