Spacesaver wheel

flybobbie said:
mcbutler said:
if you run different sized wheels on the rear for any distance you will seriously damage your differential, it will overheat very quickly.
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I think the saver wheel is 17 inch but the tyre diameter same as std. tyre.
That doesn't change otherwise the speedo would be inaccurate.
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And the traction control would throw a wobbly.
 
step_change said:
Still no nearer to knowing if a 17" will fit over the front brakes guys. I will have to go ask at BMW.
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No it won’t...
 
Pbondar said:
mcbutler said:
if you run different sized wheels on the rear for any distance you will seriously damage your differential, it will overheat very quickly.
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That’s incorrect...for normal differentials, ie non LSD or locking ones, there is no stated limit on time / distance with uneven size wheels..

Even more complex cars like my XC70 with permanent 4 wheel drive don’t specify a limitation..

Given you are only supposed to use the space saver at limited speed for a limited distance your assertion is incorrect..IMHO..

Can you show an example listed in an owners manual pls?
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Years ago I had a Mitsubishi Shogun and if it was used in 4wd with tyres new on one axle and used on the other - the car had to be reversed before it would go back into 2wd - Mitsubishi said this was quite normal.
Just to muddy the waters, this is from the handbook from a 2006 A4 Audi Quattro - From memory it had a Torsen Mech centre diff.
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I did say normal differentials Ron, as fitted to all Z4s without exception..although in this case the torque sensing diff was the centre one...so it’s kind of strange...the difference between two dissimilar wheels on one axis would impose an issue, if there was one, on the front or rear diff...the sum of each diff would be fed to the centre..I guess the variation of an axle could be fed through to the centre axle and cause issues..

As I said we are talking about relatively short distances at relatively low speeds and by implication low cornering forces..

I think issues with abs/dsc may prevail proportionally more on things..
 
The centre diffs on the Mitsubishi and Audi were mechanical - but a differential “allows” slip - I don’t think it’s supposed to be working hard for it’s living and for that reason and your abs/dsc comments I would also err on the side of caution and only use if I had to for a short distance at a moderate /low speed.
 
Didn't think there was anything special about the std. diff.
Where would it slip.
I would have thought it just reacts as though constantly on a slow curve, even when straight.
One wheel speed up a touch and the other slow down a touch.
 
ronk said:
The centre diffs on the Mitsubishi and Audi were mechanical - but a differential “allows” slip - I don’t think it’s supposed to be working hard for it’s living and for that reason and your abs/dsc comments I would also err on the side of caution and only use if I had to for a short distance at a moderate /low speed.
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I can tell you for a fact that once you’ve fitted a space saver to a heavy/high performance car you’ll be highly motivated to swap it out for a normal wheel ASAP...
 
ronk said:
As bad as that?
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On my xc70 on summer wheels I have a space saver, collected a destroyed tyre in Newcastle and had to use the space saver to get back home in Scottish Borders.. :headbang:

People who know my driving style know that in the past I’ve not always respected speed limit advise.. :rofl:

Well any speed near or over 50mph resulted in an extremely unpleasant feeling of impending doom/loss of control, I figured 3 good tyres was enough, very definitely missed a good 4th wheel...

So a space saver is an in extremis device...if I was expecting to do any significant mileage I’d used a plug / sealant in the tyre if the tyre wasn’t otherwise damaged..

I have 3 space savers for the xc, mini, z and they are absolutely get you to a base only devices... :fuelfire:
 
In my opinion space savers are a flawed logic solution to a potential problem - There has to be a space to put the full sized punctured wheel? No doubt wet and covered in muck - So why not carry a full sized wheel?
 
ronk said:
In my opinion space savers are a flawed logic solution to a potential problem - There has to be a space to put the full sized punctured wheel? No doubt wet and covered in muck - So why not carry a full sized wheel?
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Because it’s less inconvenient to carry around a smaller wheel for long periods of time than it is a bulky, full sized one? :?
Rob
 
Smartbear said:
ronk said:
In my opinion space savers are a flawed logic solution to a potential problem - There has to be a space to put the full sized punctured wheel? No doubt wet and covered in muck - So why not carry a full sized wheel?
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Because it’s less inconvenient to carry around a smaller wheel for long periods of time than it is a bulky, full sized one? :?
Rob
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I understand that part as most of the time the boot space is empty - hence, plenty of room for a full size spare.
Going on holiday the boot space is limited - No space for a full sized spare only a space saver - What happens after a flat?
 
ronk said:
Smartbear said:
ronk said:
In my opinion space savers are a flawed logic solution to a potential problem - There has to be a space to put the full sized punctured wheel? No doubt wet and covered in muck - So why not carry a full sized wheel?
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Because it’s less inconvenient to carry around a smaller wheel for long periods of time than it is a bulky, full sized one? :?
Rob
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I understand that part as most of the time the boot space is empty - hence, plenty of room for a full size spare.
Going on holiday the boot space is limited - No space for a full sized spare only a space saver - What happens after a flat?
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Rats tails! :P
Rob
 
On an E89 the space saver doesn’t really work if you are touring..unless you regulate yourself to driving with the top up with your baggage and space saver en route, then , when getting to your stop, getting your luggage out, then ,cruising locally with your top down and space saver in the boot...depends on your level of paranoia..the reality isrun flats are destroyed within 50 miles and are a mandatory replace as soon as they go flat ..so there is no easy solution..even my xc70 doesn’t have a wheel well that can take a full sized wheel :headbang:

A local colleague ex special ops police says they used rat tails / plugs as fixed often for 100s of miles at very naughty speeds :driving:
 
My local tyre fitter uses rat tails for lorries and tractors.
His advice was to tie a knot in them before you push them through, as they stay in more secure.
And said don't use the gunk stuff, it makes a right mess of the inside of the wheels and tyres.
 
I’ve got some rats tails in a cubby hole in the boot along with a compressor - I’d be interested in the knot procedure tho?
 
ronk said:
I’ve got some rats tails in a cubby hole in the boot along with a compressor - I’d be interested in the knot procedure tho?
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I’ve used them several times without knots, never had an issue with them :thumbsup:
Rob
 
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