Any point in a different sized spare wheel?

[fenns]

My a124 currently rides on 16" rims fitted with 215 x 55 section tyres but the spare is one of the original 8 hole 15" MB alloys fitted with 205 x 60 section tyres.
The car has ASD and I'm concerned that if I use the spare the different sizing might possibly damage it. If I have no option (thanks to a puncture, say) should I only fit the spare to the front axle or am I worrying unduly (as is frequently my wont ) Or would the car be lopsided ?

Thanks,

 

[SilverSaloon]

My a124 currently rides on 16" rims fitted with 215 x 55 section tyres but the spare is one of the original 8 hole 15" MB alloys fitted with 205 x 60 section tyres.
The car has ASD and I'm concerned that if I use the sapre the different sizing might possibly damage it. If i have no option thanks to a puncture should I only fiot the spare to the front axle or am I worry unduly (as i frequently my wont ) Or would the car be lopsided ?

Thanks,

my old W208 CLK had ASD and that had a smaller space saver spare wheel but rode on 17" AMG alloys.

I used the spare and didnt have any problems.

 

[stats007]

It would be interesting to know what the tolerance was on ASD, ESP etc.

 

[BTB 500]

My a124 currently rides on 16" rims fitted with 215 x 55 section tyres but the spare is one of the original 8 hole 15" MB alloys fitted with 205 x 60 section tyres.

The rolling radius is what matters, and those two setups are virtually identical in that respect (circumference is ony 2.5% different) so it should be fine. As mentioned, many cars have space-savers that are thinner than standard. Others have wider wheels at the back than the front, so obviously a spare can't match both!

 

[stats007]

Which is basically the same as having one new tyre and one on the legal limit.

 

[fenns]

SilverSaloon, BTB 500 - thank you for the reassurances

I know that on my MX-5 turbo which runs on 15" rims with 205x50 section tyres I have been warned NEVER to use the standard spacesaver on the rear axle because it will damage the Torsen diff. The standard wheel size for the car is 14". I must admit that I thought this warning all a bit "helf and safety gorn mad" when one coinsiders the Torsen is a hefty chunk of metal dealing with over 200 bhp (on my tuned vehicle) but an engineer friend explained that difference in radii (sp?) would cause damage in short order. Ditto the advice never to tow with the rear wheels on the deck

 

[Dieselman]

Ditto the advice never to tow with the rear wheels on the deck

How do you expect to pull aything if the rear wheels aren't on the deck...