Golf Space saver tyre @ 120km/h

[scotty1991]

I'm really curious as to how the ABS controller can recognise a space saver wheel and adapt accordingly. The tyre has the same rolling diameter, and therefore the ABS wouldn't know any difference, and the TPMS wouldn't either. Hence I think your theory is wrong.

Further than 200km distance is much more likely to be due to the skinny motorcycle tyre being bald after 200km than anything to do with ABS.

I dont think it would go bald after 200km without some serious effort

[gerhard]

I dont think it would go bald after 200km without some serious effort

In your case it wouldn't make the end of the street.

In the hands of a normal driver, it would only go more than 200k on the front if you drove 200k in a straight line without stopping.

[logger]

I'm really curious as to how the ABS controller can recognise a space saver wheel and adapt accordingly. The tyre has the same rolling diameter, and therefore the ABS wouldn't know any difference, and the TPMS wouldn't either. Hence I think your theory is wrong.

Pretty simple really - Nothing to do with rolling diameter - all to do with rubber on the road. Wheel with the Space Saver will reach the ABS regulation range sooner than the standard wheel. Or in other words the ABS controller recognises the difference in slip/skid behaviour of a wheel that has ~10cm of rubber on the tarmac as compared to one that has >20cm and brakes each wheel accordingly, going easy on the skinny one as it will lock up first. If the car had brake temp indication this would become glaringly obvious if you were to brake heavily.
But it is only my theory, that VW have changed their policy due to the improvements in ABS capabilty - I am most probably quite wrong - if you want to disprove it Gerhard chuck your spare on the front and do an emergency stop. I expect the car will stay essentially straight. Do this with an old car sans ABS and it will not.

Further than 200km distance is much more likely to be due to the skinny motorcycle tyre being bald after 200km than anything to do with ABS.

Very much doubt it. My space saver has done 300km (albeit on the rear) and it still has the new tyre paint stripes showing on the bottom tread.

Do you have a better theory as to why VW now recommend fitting the space saver to the front axle of the newest cars when they did not in the past?

[gerhard]

Pretty simple really - Nothing to do with rolling diameter - all to do with rubber on the road. Wheel with the Space Saver will reach the ABS regulation range sooner than the standard wheel. Or in other words the ABS controller recognises the difference in slip/skid behaviour of a wheel that has ~10cm of rubber on the tarmac as compared to one that has >20cm and brakes each wheel accordingly, going easy on the skinny one as it will lock up first. If the car had brake temp indication this would become glaringly obvious if you were to brake heavily.
But it is only my theory, that VW have changed their policy due to the improvements in ABS capabilty - I am most probably quite wrong - if you want to disprove it Gerhard chuck your spare on the front and do an emergency stop. I expect the car will stay essentially straight. Do this with an old car sans ABS and it will not.



Very much doubt it. My space saver has done 300km (albeit on the rear) and it still has the new tyre paint stripes showing on the bottom tread.

Do you have a better theory as to why VW now recommend fitting the space saver to the front axle of the newest cars when they did not in the past?

I see where you're coming from now - as I said, it's nothing to do with the ABS "knowing" there's a space saver wheel on the car. The ABS continues to assess the grip of each wheel based on the grip of each wheel, not on what type of rubber is installed. The newer version of the controller would be expected to be an improvement over the old, but it doesn't have eyes yet

300ks on the back would be fine, as you've experienced. But I maintain that on the front you could shred one very easily when weight, cornering, understeer, bump steer, traction and braking come into play. Of these forces pretty much only braking affects the rear

[SoVeReIgN]

Id say 200km limit on the front is because the space saver is very soft rubber and I bet the rolling diameter is quite different after 200km.

[Transporter]

The ABS continues to assess the grip of each wheel based on the grip of each wheel, not on what type of rubber is installed. The newer version of the controller would be expected to be an improvement over the old, but it doesn't have eyes yet

300ks on the back would be fine, as you've experienced. But I maintain that on the front you could shred one very easily when weight, cornering, understeer, bump steer, traction and braking come into play. Of these forces pretty much only braking affects the rear

No need for eyes Gerhard.
The wheel speed sensor monitors the speed of each wheel and sends AC voltage signal (which frequency changes with wheel speed) to ABS controler.. It doesn't assess the grip. It measures RPM of each wheel.

The no.1 job of the ABS is, to not allow the wheel to lock up, since the tyre with less contact area with the road will slow down faster during braking and ABS controller will apply less pressure through the hydraulic circuit for that wheel preventing lock up.

[gerhard]

No need for eyes Gerhard.
The wheel speed sensor monitors the speed of each wheel and sends AC voltage signal (which frequency changes with wheel speed) to ABS controler.. It doesn't assess the grip. It measures RPM of each wheel.

The no.1 job of the ABS is, to not allow the wheel to lock up, since the tyre with less contact area with the road will slow down faster during braking and ABS controller will apply less pressure through the hydraulic circuit for that wheel preventing lock up.

It does assess the grip, by measuring the relative speed of each wheel.
It does NOT care and can not know what sort of tyre is on the wheel. But arguing semantecs here.

Wheel turning to slowly for road speed? - release brake pressure. - ABS

Wheel too fast for road speed? Apply brake (and/or engine power reduction). - TC

Wheel pointing in wrong direction? eg understeering into corner - apply brakes of any of the wheels and/or reduce power. ESP.

In none of the above functions does the controller know what tyre is fitted. But I daresay that the ESP calibration, which is based on the "normal" grip level of the (say) 225 tyre, might be seriously confused if called upon while using the gripless skinny tyre up front, prehaps resulting in over-corrections.

Another reason to keep the skinny on the back, even on a MK VI

[Treza360]

I can't fit my space saver over the front brakes anyway.
Cheers,
Trent

[Maverick]

Hate to spoil the party chaps, but before this line of thinking becomes gospel, some clarification is required. Within the realms of this MK5 thread you are quite correct. However just so the wider community who read this are not confused, it is no longer necessary or recommended by the manufacturer with the MK6.

The Mark 6 Golf the 16" space saver spare can happily go on either front or rear axle. There is no placard precluding front fitting on the wheel it self. The Warning section of the manual states... "Do not drive further than 200km with a 16 inch space saver tyre fitted to the front axle". It also mentions not fitting 2 space savers concurrently.

I imagine the reason this limitation has been removed is due improved capabilities of the newer MK60EC1 ABS controller. I expect it does a better job of recognising the spare is fitted and adapts accordingly. Further the 200km distance limitation would possibly be to prevent unwanted long term controller adaptation. Maybe to prevent transmission issues as well.

In any case There is No requirement to change two tyres when you get one flat if you have a MK6. Space save can go on front or back But by all means do the double change if you are not comfortable with the manufacturers recommendations for the new cars.

The space saver can be fitted to the front on the Mark V.

It's not recommended however for the front due to safety.

There's no difference with the Mark VI except different wording in the manual.

The ABS controller plays no part as it has no idea if there is a space saver fitted and there's no long term adaption that can be affected nor will there be any problems with the transmission as it's an open diff.

IMO Volkswagen should continue with their recommendation of not using the space saver on the front. Stupid people will still continue to use the space saver on the front for extended periods and those that are smarter will use it on the rear for a limited period.

[logger]

The space saver can be fitted to the front on the Mark V.

It's not recommended however for the front due to safety.

There's no difference with the Mark VI except different wording in the manual.

The ABS controller plays no part as it has no idea if there is a space saver fitted and there's no long term adaption that can be affected nor will there be any problems with the transmission as it's an open diff.

IMO Volkswagen should continue with their recommendation of not using the space saver on the front. Stupid people will still continue to use the space saver on the front for extended periods and those that are smarter will use it on the rear for a limited period.

Glad you suffixed all that with IMO. To say the MK6 EC1 ABS Controller plays no part in this is just speculation. Maybe it does - maybe it doesn't. The RossTech vagcom blokes haven't even got their hands on this newer Brake Control Module yet, so it strikes me as fairly unlikely that its adaptation capability or what if any improvements it has over the previous version is widely known yet!

Amongst all the speculation and semantics floating around here, no joy will come until someone can actually establish..
Why Volkswagen policy recommends fitting Space Saver Spares to any axle including the drive axle on the MK6?
Was this change made to save printing costs, or for commercial, marketing, legal or technical reasons? I would like to think advances in technology have allowed the latter. But until someone can get a definitive answer from VW we are all just speculating.

IMO just RTFM

[Maverick]

Glad you suffixed all that with IMO. To say the MK6 EC1 ABS Controller plays no part in this is just speculation. Maybe it does - maybe it doesn't. The RossTech vagcom blokes haven't even got their hands on this newer Brake Control Module yet, so it strikes me as fairly unlikely that its adaptation capability or what if any improvements it has over the previous version is widely known yet!

Unless the ABS controller has some kind of wheel recognition system there is no way for it to tell that you have a space saver fitted. As it doesn't have this there is no speculation.

Amongst all the speculation and semantics floating around here, no joy will come until someone can actually establish..
Why Volkswagen policy recommends fitting Space Saver Spares to any axle including the drive axle on the MK6?
Was this change made to save printing costs, or for commercial, marketing, legal or technical reasons? I would like to think advances in technology have allowed the latter. But until someone can get a definitive answer from VW we are all just speculating.

• Putting a space saver on the front is stupid. The front wheels steer and the weight of the car transfers during braking to the front of the car. I've seen the results of tests with spaces savers and you're looking at ~5-10% braking distance increase with a space saver on the rear and ~15-40% on the front.
  
• Space savers are intended for short distances and limited speed, the tyres can have a life as little as 500km.

As for why VW don't care, part of this would be that they're intended for short distances at low speed. Be saying you can fit them to the front or back it get's people off the side of the road quicker.

Doesn't really matter why but it's smarter to put the spare saver spare on the rear, stupid people won't read manuals and will continue to drive for extended periods at speed on space savers fitted to the front wheel. Consider it as a warning sign to keep clear of them.

[CatonaPC©]

The space saver can be fitted to the front on the Mark V.

It's not recommended however for the front due to safety..

What about fitting it to the front and driving slowly to the nearest tyre repairer?

[gregozedobe]

What about fitting it to the front and driving slowly to the nearest tyre repairer?

I guess it is up to you (and how far is "near"). Excessively slow vehicles are often involved in accidents.

[Maverick]

What about fitting it to the front and driving slowly to the nearest tyre repairer?

As Greg said it's up to you but if were on the shoulder of a highway or in a bad location I'd put it on the front until I was about to get somewhere safe and swap it to the rear.

You can fit a full sized spare to the boot as well. I've thought about it but I never used the spare in my last car in 5 years of owning it, have only used my spare once on the GTI in 18 months and only covered around 13km's in 3 trips so I'm not sure I'd bother with it unless I get a get a spare alloy cheap.

[gerhard]

Wonder what a spare steely from the Golf V or VI would cost. Maybe a relatively cheap 16" wheel & tyre would take up less room in the well than a 7" alloy with a 225 on it.

Not worried around town, but it could be a pain when more than an hour from home. Who's going to trust a country servo to fix a puncture on a Denver without screwing the wheel over.

Forgot to add, a "normal" 16" steely would be far safer than the crapola 80k thing.