space saver tyre

[Castleby]

I have a space saver tyre which I bought for my previous B 200.
It is marked T 125 / 90 R16 98 M. My current B200 has tyres marked 225 / 45 R18 W.
When I went to MB for the first service on the car I asked them if this would fit. The message did not get through to the garage (not the first time) and when i went to pick it up, I asked the receptionist. He said that next time I took the car in, they would be happy to try the tyre / wheel on the front and back to see if it fits (apparently the studs my be a different length and the brakes are different front and back).
Can anyone give a definitive answer please?

 

[Blobcat]

Diameter is an 1” different or ~4% which would be enough to throw up ABS and ESP codes. For an emergency to get you home it might do - I’d check it fits on the front - if it fits over the brake calliper and the wheel bolt PCD is the same you could use it.

Although my SLK has a space saver spare 145/70 17 - my normal tyres are 225/50 16 these are 0.1” or ~0.4% different so zero issues with ABS or ESP.

 

[LostKiwi]

As above but just to add you will need different bolts as the ones for alloy wheels are too long to use on a steel wheel and will hit brake components.

Also be aware that you will generate a lot of heat in the differential with that much difference in diameter. If you do use it don't drive far or fast.

 

[Blobcat]

As above but just to add you will need different bolts as the ones for alloy wheels are too long to use on a steel wheel and will hit brake components.

Also be aware that you will generate a lot of heat in the differential with that much difference in diameter. If you do use it don't drive far or fast.

Depends on when the space saver was made - some (my ‘09 SLK) have raised bolt holes in the spare so it will use the same bolts as the alloys - always worth checking they don’t foul the gun though as they can ruin the parking brake.