Managed to cut a sidewall. Grrrr. Having a 280 with 19" wheels meant a couple of days to get a new tyre, but never mind, in the mean time I have the space saver. Limited to 50 mph is better than zero!

 

I did notice that the diameter of the space saver is quite a bit less than the normal tyre, and sure enough after a short while I got a TPMS failure, ACC failure, which seems a bit daft for a factory fit spare wheel. Having put the new tyre on, I tried to reset the tyre pressure monitoring but it was having none of it, declaring failure. Fortunately I have a VCDS and it didn't take long to reset the fault in the ABS module, but what is a normal owner without VCDS expected to do? Take it to a dealer to have the fault reset, costing £££ no doubt? Seems simply not very clever.

I have used the space saver and had no problems when the fixed tyre was put back on, just reset the system, obviously had to do it a few times, as is normal, while the tyre settled back in but no other problems.

It should be the right outer diameter even if the wheel is smaller as the tyre sidewall profile should change to match.  Have you got the right spare?  There is more than one version.

1 hour ago, FelisBengalensis said:

It should be the right outer diameter even if the wheel is smaller as the tyre sidewall profile should change to match.  Have you got the right spare?  There is more than one version.

Well it's a good point, it was visibly smaller than the 19" wheel I took off. I got he car at 6 months old, previously owned and driven by a Skoda dealership. I'd better ask...

So I checked the spare, it's a T125/70 R18, whereas the normal tyres are 235/40 R19. The outside diameter of the spare is around 30mm less than the normal tyre.

 

 I finally got around to contacting Skoda customer service, but they tell me that they've "checked the database, and the car was shipped with the correct sized spare wheel" and then go on to tell me that it's smaller because it's a space-saver etc etc.

 

Hmmmmm...

 

So, if anyone has a Superb MY16 with 19" wheels and a space saver spare, please could you have a quick look and see what size your spare is? If I do indeed have the correct spare, it seems a bit daft that it creates a hard fault in the ABS module when it's used. And probably not very good for the rear diff as that wheel will be be going quite a bit faster.

A Fabia with 205/40 R 17 tyres comes with a spare that is 195/55 R 15

 

You set the TPMS when you fit the spare then the TPMS does not alert, or might, so reset.

Temp Spare wheel in a slightly different total circumference is common. drive accordingly, (slow and safe) and set the TPMS.

Even if the spare was identical size but new, it is 'Green' so slow down as well, its an odd one out.

http://kouki.co.uk/utilities/visual-tyre-size-calculator 

 

Spare wheel to get you to a place of safety and change as soon as poss, repair or replace tyre soonest.

Edited 22 May, 20179 yr by Awayoffski

2 minutes ago, Awayoffski said:

A Fabia with 205/40 R 17 tyres comes with a spare that is 195/55 R 15

 

You set the TPMS when you fit the spare then the TPMS does not alert, or might, so reset.

Temp Spare wheel in a slightly different total circumference is common. drive accordingly, (slow and safe) and set the TPMS.

Even if the spare was identical size but new, it is 'Green' so slow down as well, its an odd one out.

http://kouki.co.uk/utilities/visual-tyre-size-calculator 

Thanks, so maybe it is not the wrong size. But just to reiterate, I fitted the spare and reset the TPMS, I then drove about 15 miles, gently and at no more than 50mph, whereupon I got a TPMS failure (not a puncture warning) and ACC failure. The only way to get rid of the underlying fault (unfeasible wheel speed reading in the ABS module) and get the TPMS and ACC back, was by VCDS. For someone without access to VCDS it would be a dealer visit to reset, presumably at significant cost.

Well there you go, presumably they would have to then.