Recommendations for donut spare tire?

Finally took delivery of my i3 yesterday. I'm looking to get a donut spare tire to put in the car. Since one is not made specifically for the i3 can the more experienced drivers out there recommend one? Maybe one made for one of the other BWM models? Thanks in advance!

I think you'll have a very hard time finding a compact spare for the i3! Keep in mind, you'll have to buy a jack and tire tools (BMW does make a nice kit with this stuff and I've been told, it does fit in the frunk). The tire/wheel is already about as small as they come. If you really want to carry a spare, you might want to just pick up a base model wheel with a tire. I don't think it will fit in the hatch without the seats being folded, though (I put my 4 winter tires in the vehicle fairly easily, but had the seats folded when I picked them up. The typical compact spare is a narrower version of the OEM wheel and a limited use tire...I wouldn't want to go any narrower, and ideally, it would have very similar OD so the handling wouldn't be affected or you wouldn't be twirling the differential constantly if it was needed on the back.

jadnashuanh said:

ideally, it would have very similar OD so the handling wouldn't be affected or you wouldn't be twirling the differential constantly if it was needed on the back.

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The traction control might be confused by a tire with a different OD as it is on the Mitsubishi i-MiEV when one installs tires of a slightly different OD than OEM even on both sides of one axle. This problem could be worse with tires of different OD's on the same axle as would happen with a donut spare. The traction control thinks a tire is losing traction when it is rotating at a different speed than expected. When this happens, regen could be turned off which would not be good.

But there must be cars with traction control and donut spares, so maybe this problem has been solved.

There are reasons the 'donut' spares have speed and distance restrictions on them. First, the tire itself is not designed with much tread, and second, it may be a difference in OD than the other wheels on the vehicle. Overall stability and hardware reliability could be an issue.

I just got back home from a drive over to the local rail trail parking lot to check out the snow cover on the trail (unfortunately, there's too much to go for a bike ride), but while there, in the maybe 2-3" of snow that was left, I floored it, and the car went all of about 3-4mph until it caught a clear spot. I could have turned off some of the safety controls, but didn't think of it at the time and try again to see how things reacted. The traction lamp was on nearly all of the time, but I could feel no actual slipping of the wheels on the snow/ice. The lot wasn't big enough to see what my maximum speed I could achieve, but I guess the important thing is it didn't get stuck and kept going.

I saw jadnashuanh's post about his spare tire solution (thanks for the link for the jack kit).

I suppose the tires is already narrow enough to make a donut too close in size to bother producing. So say I buy an extra front tire, would there be a generic wheel available so I do not have to spend around $500 just for a spare?

tezarc said:

So say I buy an extra front tire, would there be a generic wheel available so I do not have to spend around $500 just for a spare?

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No, at least, not yet. There is very little wheel choice out there and zero tire choice beyond the OEM parts. Perhaps in a few months as the number of vehicles in the worldwide fleet grows.......

As far as using a donut spare from another car: who cares if the traction control is confused and the Regen does not work? It's an emergency, just put the spare on and drive carefully home or to a garage. Driving a car without Regen is not a hazardous situation, millions do it everyday.

TireRack has both a wheel that will fit and sells the OEM tires. Probably end up costing about 1/2 that of an OEM wheel, but when you add a TPMS in it and tire, it may be a wash.

You can buy a premounted, winter tire with sensor for probably about $400 directly from BMW (retails for about $440), but the tread is directional. For short term, it would work, and you'd have a 50:50 chance of it being on the needed side.

The hassle with most temporary spares is the speed limit and distance limitations. Many people abuse them badly, but that doesn't make it safe. A full-size spare, if you're going to go that route, seems the better choice.

Since I now have two sets of tires/wheels, I suppose I could carry one around, but I don't drive the thing all that far and haven't worried about it.

WoodlandHills said:

As far as using a donut spare from another car: who cares if the traction control is confused and the Regen does not work? It's an emergency, just put the spare on and drive carefully home or to a garage. Driving a car without Regen is not a hazardous situation, millions do it everyday.

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Millions have engine braking whereas without regen, an i3 would freewheel which could be dangerous down a long hill with only brakes to decelerate.

Also, traction control tries to equalize wheel speed by applying the brakes on the wheel that's rotating faster than expected. So with a spare tire of a different diameter than the other tire on the same axle, the brakes on one wheel might be on continuously.

This is all conjecture on my part, but the traction control on my former EV, a Mitsubishi i-MiEV, would turn off regen if both tires on the same axle had a diameter that was somewhat different from the OEM tires (e.g., a non-OEM tire of a different size). Like the i3, the i-MiEV had no spare tire, but I don't recall anyone reporting its behavior with different size tires on the same axle. However, unlike an i3, the i-MiEV's traction control could be turned off.

I have never owned a car with traction control and a donut spare. Must one turn off the traction control when a donut spare is mounted on such a car? If so, then i3 drivers would be out of luck being unable to turn off traction control.

One of the reasons there is a speed limit on most compact spares is literally the tread and carcass design can't handle heat dissipation of a 'normal' tire. On the driving axle, different diameter wheels will mean that the differential will be engaged literally all of the time...they are NOT really designed for this, and could overheat, again, another reason why there's a distance and speed limitation on a compact spare. Because the tread and carcass is not the same, breaking and handling will not be the same (the compact spare typically would be much less), again, a reason for the speed and distance limitations. Different diameter assemblies also will mean that when braking, you car could think one wheel is locked up and increase your stopping distances. As far as I know, there is no way to turn that off short of maybe pulling a fuse, and then you may lose other functions enough such that the car is immobile. You may notice a decrease in the ability to accelerate, again, because the car may think one wheel is slipping since they won't turn at the same rate. Certainly people ignore these... I see people passing me on the interstate on occasion with one mounted which is really dumb.

If safety is important to you, abide by those limitations, or get yourself a full-sized spare if you feel you need one on the i3. Yes, if you've bought a jack and tools, you can change one and keep going, hopefully, to a repair shop where you can quickly get back your 'normal' tire.

New member here. Not a troll but don't own an i3, my son in law does and being a car guy I want to know more about them and what I can get for him in the way of add ons, performance stuff et. Al. Regarding not having a spare. I have had 3 cars with no spares, right now a 2012 Camaro SS. I worried about it for a while but after only 1 flat over 8 years of no spare cars I have quit worrying but do watch where I drive a little, construction sites, highway aprons with old wreck debris etc.
I looked into many alternatives for all 3 of those cars and never found a really attractive alternative.
Looking forward to reading all your postings.

alohart said:

WoodlandHills said:

As far as using a donut spare from another car: who cares if the traction control is confused and the Regen does not work? It's an emergency, just put the spare on and drive carefully home or to a garage. Driving a car without Regen is not a hazardous situation, millions do it everyday.

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Millions have engine braking whereas without regen, an i3 would freewheel which could be dangerous down a long hill with only brakes to decelerate.

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I seriously doubt that the brakes on the i3, or any BMW, are so marginal that they would need the aid of the Regen system or engine braking to safely control speed on any sort of hill, no matter how steep or how long.

The actual rolling resistance of the vehicle while coasting isn't all that much without regen. Unlike an ICE, you will have nearly no engine braking without the regen functioning, and the vehicle will reduce regen if it things the wheels are slipping. Certainly, the brakes can stop the car, but not if the hill is steep enough AND long enough where they end up overheating. Most people won't experience that, but it is a real possibility.

I guess you folks have never heard of "Hypermiling". Rolling in neutral is an integral part of the process...... Also known to truckers as Mexican Overdrive when I was a child.

The UK i3 Hypermiling owner who posts here coasts in N all the time and he has not mentioned anything about brake fade or failure. The i3 is so lightweight and the brakes are so large that brake fade when coasting is inconceivable. I have been using this technique for over 40 years driving my ICE vehicles with no brake fading at any time. It is far cheaper to replace brake pads than a clutch or a transmission so I choose to wear them out instead. BTW, I haven't had to replace my pads prematurely either.

Now if one was to load up their i3 with four 120k passengers and hook a boat up to the trailer hitch and descend Pikes Peak, perhaps you might have a point.......

The only dimensional difference between a conventional car's normal and "donut" spare is the width. The i3 tire width is already narrow, so a separate limited duty spare wheel and tire assembly would make little sense. A full duty spare can operate at much greater speeds, and for much greater distances.

You can get a mounted spare wheel and tire assembly from TireRack for as little as $364 plus shipping. I paid ~$505 for mine, which included an $80 TPM sensor (unnecessary for most folks - I added it because I occasionally take long trips in the i3) and shipping.

It will not fit in the trunk, so here's a suggestion for conveniently and safely carrying it, for those who do not regularly travel with more than 3 occupants in the car:

It fits the space behind the passenger seat perfectly with the seat slid all the way back, and comfortably reclined:



It does not interfere with lowering the seat back completely flat:



To secure it from being a dangerous projectile in an accident, give the front edge of the rear seat bench a gentle vertical tug, exposing its attach point:



Guide a strong rope around the steel support member:



Tie the rope securely around spokes at the level of the attach point. Hint - if you tie it reasonably securely before replacing the seat, it snugs everything up nicely as you push the seat bench back into position:



The BMW jack and wrench kit includes a chock and even a torque wrench (http://www.ecstuning.com/Search/SiteSearch/71102182448/ES2530819/). It fits perfectly in the width of the frunk:

That's a nice solution above, if you don't mind the cost and wasted space.

For most people, carrying a small $5 tire plug kit plus a set of pliers should cover you for 95% of punctures. In the unlikely case that you have a sidewall damage, or a puncture too large to be repaired, you could call roadside assistance.

The majority of tire failures I've experienced could not have been fixed by a plug or sealant kit.

I carry a plug kit, which can fix a flat as effectively as can the BMW goo (without trashing an $80 sensor). Problem with roadside assistance is that I lose use of the car for a day or two which is inconvenient for long trips, and career ending for my job. I do not have the option of being late or absent. With a spare onboard, I can change a flat in 10 minutes and not be late for work.

We all have different needs.

The highest paved road in England appears to be 840M, the highest one in the USA is 3, 279M. There are LOTS of long grades, primarily in the western part of the USA, but some quite significant elevation changes even on the east coast. What may work in some parts of the world would not in others. Coasting without engine braking can put a huge load on the brakes. I'm certainly not saying it will happen, but if you have no regen on your i3, essentially you ARE coasting, and brakes were not designed to slow you down continuously over miles and miles.