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DepthHoar

BMW E39 M5 spacesaver spare wheel & tyre

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After several continental trips in the M5, including one north of the Arctic circle in Norway, I thought it would be a good idea to carry a space saver tyre. Just in case. Not an fan of the can of goo 'solution' to a flat tyre in this car, so a compact spare wheel/tyre combo seemed a much better alternative to the 'cross your fingers and hope' that inevitably accompanies the can of goo approach. 

 

I know some people just use a Style 65 front wheel and tyre as a spare but they are pretty bulky. Same goes for the parallel spoke Style 66, which is a little less bulky but comes with a 'winter tyre only' warning from BMW, though I'm sure you could use a summer tyre to little or no ill effect.

 

But I wanted small, and small as possible since I tend to travel heavy, if you get my drift.

 

There have been loads of threads on this issue across this forum and the M5board to name just two. One M5board thread I found to be the most useful, and in particular the thoughts of a British forum member who posted this:-

 

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All of it seemed to check out. The BMW steel rim he suggests was verified as a good fit both in bore size, bolt pattern and wheel offset. The tyre size choice seemed good too. But. He posted his comment back in 2014 and the tyre size and brand he recommends is no longer stocked at the moment by anyone in Europe, least of all Camskill. Same goes for that size tyre size but from different manufacturers. (However, I believe Maxxis may sell a tyre, but only available in the USA, that will work for this application).

 

A dead end then, at least here in the UK? I gave up looking after a while but revisited the issue earlier this year.

 

Looking back I'd become a little too focused on sourcing a a 155(mm) wide tyre to fit the 5" BMW steel rim.That size is the ideal fit but having spoken to my trusted local garage owner and tyre supplier he reckoned a 145(mm) wide tyre would be fine on a 5" rim since 145mm is 5.75". 

 

After playing around with some online rim/tyre size comparison tools I came across a 145/70/18" 'temporary' tyre manufactured by Bridgestone that seemed to fit the bill. See below:-

 

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(Above) Standard FRONT wheel and tyre size compared to the proposed spacesaver wheel/tyre combo. Diameter/circumference are within acceptable limits: +1.2% of the standard size.

 

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(Above) Standard REAR wheel/tyre size vs. the spacesaver. And +1.6% in this instance.

 

Note the different tyre sizes at the front and rear on the M5 as fitted at the factory. That comparison results in a 0.5% difference in diameter/circumference front/back or back/front as standard.

 

Game on then.

 

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(Above) The wheel from BMW. £61 from Cotswold when I bought it a year ago. Note that it's the spare wheel for an E70 X5.

 

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(Above) The wheel/ tyre combo as fitted.

 

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(Above) The Bridgestone model and size. Technically it's a TRR2, I think. Available from Camskill for £55.70 today (May 2020) + delivery and fitting.

 

So, about £130 all in. My tyre was manufactured in Week 37 of 2018 so it's not some cracked & perished OAP of a tyre either. I came across several scruffy used spare wheel/tyre combos on eBay that might have worked but with DOT marks at least a decade or more old! Ridiculous prices being asked too. 

 

Proof of the pudding time. Does it fit the car and clear the brake calipers?

 

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(Above) The front. Can confirm that the bore size and bolt pattern are perfect, there's decent clearance of the calipers and no problem with the wheel arch. The standard wheel bolts work absolutely fine as well. Not sure this set up would work with a big brake kit - you'd need to research that very carefully before committing to it.

 

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(Above) Gimp tyre in my wheel arch!! Standard fitment over on the right.

 

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(Above) Holy bejasus! That is quite a contrast to the 275mm wide tyre that normally resides there. So, the temporary spare is a functional fit, clearing everything with sufficient space for normal suspension travel.

 

If you have lowered suspension you'd need to assess this particular application very carefully, a lot depending on how slammed your stance is. Mine is an utterly stock suspension set up and it works fine at both ends.

 

Other issues:

 

The load rating of the new spare.

It's rated as 107, which is 975kg. OE standard fitment is circa 97 to 99 load rated, which translates as 730 to 775kg. No problem there then, though you need to keep the spare at the recommended 60psi for that load rating.

 

Car insurance implications.

A bit of an unknown and will depend on how your insurance company views this. So do your due diligence. My two cents is that it's a temporary spare, limited to 50mph and will only be used to get the car to the nearest tyre outlet for a repair or replacement of the punctured tyre.

 

Carrying the spare in the M5.

 

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(Above) The M5's massive rear exhaust boxes means the space normally reserved for a spare wheel in other E39 saloons can only accommodate the 12v battery, the tyre inflator and emergency cans of goo.

 

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(Above)  By way of contrast, the spare wheel well in my E39 530d

 

 

(To be continued)

 

 

 

 

 

Edited by DepthHoar

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Continued:

 

Carrying the spare in the M5

 

Bought a tyre sock thing for it made by Heyner of Germany, though I'm pretty sure it's made in China. New for £8 on eBay

 

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(Above) Good fit in the M5's boot with quite a lot more space than than the bigger alternatives.

 

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(Above) You'll also need to carry this lot to effect a successful wheel change. Don't overlook the locking wheel bolts. They require a bigger hex pattern socket than the standard wheel bolt. The wheel brace for the locking wheel nut is an old one I had lying around from a Subaru I used to own. The jack is from my E39 530d and has the correct pattern shoe on it to fit BMW jacking points.

 

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(Above) The M5's tool kit. Already has the pre-prepared slot for the wheel brace so has a more OE look. However,  I might buy one of those 1/2" drive telescopic wheel braces and carry a couple of the correct size sockets. I think it would make a road-side wheel change a bit easier -  a much longer lever etc. - than the BMW/Subaru mix I have at present.

 

This hybrid temporary spare arrangement I've put together is not for everyone. Some might have issues with the insurance angle, others may prefer a bigger spare. My requirement was to create as much boot space as possible and have a functional spare to get me out of trouble and keep me mobile in isolated locations a long way from home.

Edited by DepthHoar

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