Spare tire well - wheel fitment/clearance.

[85e28m30big6]

Hey folks,
Since I'm not completely knowledgeable about our e28s, I'm curious about a clearance issue. Now I believe, based on what I've read that the M5 has a 16" (?) basketweave residing in the spare tire well. Therefore, can anyone verify if a 16" rim will fit without clearance problems, like a big lump in the trunk space of my 535i? I'm going to upgrade to a 16" wheel/tire combo and I am considering a 5th for a spare to replace the TRX that's in the well now. I think the rims will be 16 x 7.5 and I expect to run 225/50s on them. Anyone else doing this with one in the spare well?
Thanks!

[DRP535]

I have some experience with this issue because I was looking to do exactly the same thing. Yes, you're right, the M5 does have 5 identical wheels however it also has a completely unique boot trim on the floor. It consists of just carpet. Maybe it's rubber backed as well I don't know, but it does not incorporate the hard backed reinforced section that goes over the spare wheel well of all the other cars. This allows the slightly wider spare wheel to sit there without creating a bulge in the boot floor and making it unstable. There is a piece of plywood that goes over the wheel itself to prevent the carpet from falling into the wheel.

In lesser models the boot floor trim incorporates a quite thick and hard reinforced section to support the weight of anything being carried over the spare wheel. If you fit an M5 wheel with a 225/50-16 tyre fitted to it in the spare wheel well with that boot floor trim over the top of it you will have a visible bulge in the floor of the boot and it will teeter like a see-saw making things rather unstable.

For this reason I kept my pristine TRX 220/55-390 spare and attached a genuine Alpina sticker which warns about the performance drop to be expected when using a spare wheel with a different specification to the road wheels. This leaves me with a perfect looking boot and yet still looks reasonably genuine.

[BRRV]

Agreed - I have a 16x7.5 Style 44 wheel mounted on a 225/50-16 tire and it will not allow the trunk floor covering to fit as designed. I leaves a noticeable hump, as the wheel will protrude above the floor. Do you use a separate set of winter wheels, such as a 15" E34/E32 wheel? If so, perhaps you could match the spare wheel to that set, if it will fit - I've not tried it with mine yet, as they are still on the car. Otherwise, if memory serves, Discount Tire (USA) offers a new, reasonably priced (50.00) 15" steel wheel in a BMW fitment for our cars. Or, you could just find a used 14" BMW steel wheel, which was the alternate (non-TRX rim) fitting for these cars.

[Mark 88/M5 Houston]

Save a bit of cash and keep the best of the TRX's as the spare.

[Mike W.]

Like others, I can confirm that big 16's don't really fit in the spare tire well and allow a flat trunk. But it could be worse.

On my E39 528i there is a plastic spacer about 2" thick over the whole trunk floor with the exception of the spare tire area. And the spare is way down there. I'm guessing it's to allow the optional 17's with bigger tires to fit fine, but I'd love a bigger trunk, an extra 2" would make for a lot more room in there. Ahhh, the luxury of a smaller trunk. Not.

[DRP535]

FWIW I think the hard folding floor piece is a far more elegant and better looking solution than having what the M5 has. In this case where you must choose between having the proper boot floor trim or having a matching spare wheel/tyre combination, I think it's actually better to have the proper floor trim. It's the only thing I can think of that's actually better in the lesser models than in the hero model ///M5 of the range.

[cgraff]

Yes, if you put in 225mm wide tires, there is most likely going to be a problem with the carpeting having a bulge, as stated.

In my situation, I have a stagger set of Hartges on the car, and wanted to have a 16x7.5" spare. Given the offset issue of running a front Hartge on the rear, I couldn't put a 225/50 tire for the spare on - otherwise it'd rub on the rear. So I bought a 205/55 non-directional tire to use as my spare. Works just fine with no bulge.

Why did I need a 16" Hartge spare? Bigger brakes - the TRXs wouldn't fit over them.

-Chris

[85e28m30big6]

Hey all,

Thank you very much for the info. I think I will stick with the TRX as a spare (stock brakes) and save myself some $ by only buying a set of 4 - 16" wheels/tires.

Once again, thanks! Your input was very valuable!

[DRP535]

So I bought a 205/55 non-directional tire to use as my spare.

That's a bloody good point that I hadn't thought of Chris! The spare does need to be a non-directional tyre of course! I can't believe I didn't think of that. If I had been smart enough to realise that I could have saved myself a whole lot of bother test fitting my (directional) tyre mounted M5 wheels in the spare wheel well to see if they fitted when I was looking at doing the same as what the OP has been asking about. Realising that the spare needs to be non-directional would have made me come to the conclusion that it was a bad idea so much quicker! I came to the right conclusion in the end anyway, it just took me a bit longer and with a lot more effort.

[KillerPM]

but isn't the TRX tire directional?

Would it really matter if you run a tire backwards for a couple of hundred kilometers until you get the proper tire fixed?

[DRP535]

but isn't the TRX tire directional?

Nope. TRXes are non-directional.

[M635CSi]

but isn't the TRX tire directional?

Would it really matter if you run a tire backwards for a couple of hundred kilometers until you get the proper tire fixed?

Wasn't the original spare in the E28 M5 directional?

[DRP535]

but isn't the TRX tire directional?

Would it really matter if you run a tire backwards for a couple of hundred kilometers until you get the proper tire fixed?

Wasn't the original spare in the E28 M5 directional?

I don't think the P700 as fitted OE to the E28 M5 was directional no. I'm more than willing to be proved wrong on that however. Certainly the current generation P700 tyre by Pirelli is not directional.

[Tammer in Philly]

Would it really matter if you run a tire backwards for a couple of hundred kilometers until you get the proper tire fixed?

Directionality only matters in the wet.

-tammer

[M635CSi]

but isn't the TRX tire directional?

Would it really matter if you run a tire backwards for a couple of hundred kilometers until you get the proper tire fixed?

Wasn't the original spare in the E28 M5 directional?

I don't think the P700 as fitted OE to the E28 M5 was directional no.

The P700 in the trunk of mine is (directional) and I was told it's the original spare but I can't say for sure it is the original...

[DRP535]

Directionality only matters in the wet.

Which unfortunately is exactly when you're most likely to get a puncture, and not only because of Murphy's Law, but also because water is a natural rubber lubricant facillitating easier object penetration.