[popopine]

Quick report: I was able to fit a BMW space saving spare under the regular trunk of my M40i. Here's how. First I removed the trunk floor. There are 4 torx screws underneath that hold the hinges together on each side. I put the tire down and drew a circle around it. I used a utility knife to cut out a generous hole in the subfloor--which I figured would help keep the wheel in place.

Now I see why they raise the trunk. The tire really doesn't fit longways between the metal frame behind the second row and the battery at the back. The tire is a looong 26" and the space is a short 25.5". And that was the toughest part. I won't go into every thing I tried. I'll just say it took me the better part of the day to figure it out. I took about half the air out of the tire and jammed it in.

Anyway, I wrapped the the jack and put it horizontally in a sunken space right in front of the battery, beneath the tire. The rest of the goodies went wrapped in the space saving wheel well, including 2 emergency chains that I can put on on a stuck tire, without taking the wheel off. Put some padding on top in case I wanna drive like an nut so things don't bounce around. Put the trunk floor back on and shut it all snug.

(I ordered separate from getBMWparts.com and boy it still ain't cheep) Note: I did get the jack carrier, it wound't fit vertically.

Sorry for the bad images: don't know why they're coming in sideways... but you get the idea.

[rkx3m40i]

Originally Posted by popopine

Quick report: I was able to fit a BMW space saving spare under the regular trunk of my M40i. Here's how. First I removed the trunk floor. There are 4 torx screws underneath that hold the hinges together on each side. I put the tire down and drew a circle around it. I used a utility knife to cut out a generous hole in the subfloor--which I figured would help keep the wheel in place.

Now I see why they raise the trunk. The tire really doesn't fit longways between the metal frame behind the second row and the battery at the back. The tire is a looong 26" and the space is a short 25.5". And that was the toughest part. I won't go into every thing I tried. I'll just say it took me the better part of the day to figure it out. I took about half the air out of the tire and jammed it in.

Anyway, I wrapped the the jack and put it horizontally in a sunken space right in front of the battery, beneath the tire. The rest of the goodies went wrapped in the space saving wheel well, including 2 emergency chains that I can put on on a stuck tire, without taking the wheel off. Put some padding on top in case I wanna drive like an nut so things don't bounce around. Put the trunk floor back on and shut it all snug.

(I ordered separate from getBMWparts.com and boy it still ain't cheep) Note: I did get the jack carrier, it wound't fit vertically.

Sorry for the bad images: don't know why they're coming in sideways... but you get the idea.

That's incredible! So the floor doesn't need to be raised, right? Do you need to buy all those bmw parts or could you just buy an inexpensive jack and accessories (non bmw), does the spare need to come from bmw or would an aftermarket rim of the same size fit? I would like to get rid of my run flats but only if I can have a spare onboard. Will cutting the sub floor have any negative side effects, like sound insulation, structural strength, etc? I've never looked at that area very closely. It's awesome what you did, thanks for posting.

[Alias1431]

I'm conflicted in how I feel about this.

[popopine]

Originally Posted by rkx3m40i

That's incredible! So the floor doesn't need to be raised, right? Do you need to buy all those bmw parts or could you just buy an inexpensive jack and accessories (non bmw), does the spare need to come from bmw or would an aftermarket rim of the same size fit? I would like to get rid of my run flats but only if I can have a spare onboard. Will cutting the sub floor have any negative side effects, like sound insulation, structural strength, etc? I've never looked at that area very closely. It's awesome what you did, thanks for posting.

Thx! And that’s exactly why I did it. No more runflats. The car is a dream to drive with regular tires. To your questions. I would buy the bmw wheel and tire because the after market ones I’ve seen are too large. Everything else you can get on your own and save a ton. The subfloor is a thin layer of pressed fiber. I doubt it does much in way of sound deadening. In fact I would bet the tire eats more noise that what I removed. And most of it is still there holding the tire in place. The trunk floor is actually pretty stiff but I plan on throwing one of those EVA gym floor squares between the wheel and the trunk floor to tighten it all up and give support.

.

[Hendoo]

Brilliant. And thanks for sharing.

So deflating the spare was the key to avoiding the raised floor? Great solution.

How tight is the fit?

Is there any reason not to completely deflate it?

Great post.

[Cabman]

Did you lose the space to stow your cargo cover by doing this? It looks like it's stowed in one of the photos but I just want to be sure.

[JayPichardo]

Nice!!

[Eclimax13]

Great job. How much of an improvement have you noticed by ditching the runflats?

[teaston]

I don’t understand why BMW didn’t do this instead of raising the boot floor!?

[MADBMWX5MC]

Popopine, so the spare tire/rim you posted costing $214.27 and $125 clear our big breaks ?

[popopine]

Thanks for the positive feedback everyone. To answer a few questions. Not gonna lie, the fit is tight. You really have to get that spare seated all the way on the floor. I would imagine you could take more air out but I didn't want to risk breaking the bead seal where the tire meets the rim.

Yes, you will lose the spot to store your cargo cover.

According to getbmwparts.com where I got the goods, it lists the wheel and tire as GO1 compatible. They were very helpful in making sure my items matched. That said, I did not mount the wheel myself to double check. but I'm confident it will clear the brakes.

Are non-runflats worth it? Here's my recent post on swapping out my RF for NRF. https://x3.xbimmers.com/forums/showthread.php?t=1615663

[mattchops]

What did you do with the red cables/wires that seem to be in the way in the second photo? Does the tire just sit on top of them without an issue or did you find a way to get them out of the way?
Thanks for sharing your process, btw. I've thought about doing this myself.

[popopine]

Go for it! Yup the red cables float just under the tire in space attached to the battery bracket with zipties.

[383vett]

Great job!

[coupegt]

I might try this mod, once my stock tires are worn...... I hate RF's

[Crypto2k3]

You are awesome OP! Nice work

[Hendoo]

Awesome post. You have big brass ones to be cutting up your car like that.

Any idea if you could use one of the VW/Audi inflatable spare tires?

They have a much smaller circumference, so would fit into the small space easily.

[_ink]

Ingenious!!!

I was just thinking about solutions for when I change out the RF tyres. In my previous E92, BMW included some Slime like product with a 12v air pump, this is much much more robust as a solution.

[Cincinnati Wolf]

I’m curious how “popopine” likes this nearly a year later. Has anyone else done this mod?

I really want a spare so I can switch to non-RFs but we don’t want the raised floor. We are planning to order a 2021 M40i as soon as the order sheet comes out. Maybe BMW decided to fix this afterthought spare situation. 😉

[Alias1431]

I feel the same, but the biggest mod I'm willing to do is add that strut...

[sbt007]

If air is taken out of the spare to fit the space, does that not defeat the purpose when you need it. Unless there is a way to inflate it.
I also wanted this option but was annoyed at the raised floor and have not ordered yet.

[Alias1431]

Originally Posted by sbt007

If air is taken out of the spare to fit the space, does that not defeat the purpose when you need it. Unless there is a way to inflate it.
I also wanted this option but was annoyed at the raised floor and have not ordered yet.

Just get a small pump that can plug into 12V. Amazon has plenty.