Hi everybody.

I thought you might like to have a look at an experiment I did today, as I've been trying to think of a way to squeeze a larger tyre into my spare wheel well without potentially having to smash & bash or put it on the roof.

I have a 2016 SJ and my stock tyre is 225/60/17. I have bought some 16 inch rims with a view to going either 215/70/16 or possibly 225/70/16 but the problem as others have found is that there is very little excess room in the spare wheel well. Anyway, since the car is still quite new I don't want to bash the metal or cut anything or make a major modification like a rear bar to take a spare. So, the main options I have been thinking of are either having a deflated tyre as a spare or putting the spare on the roof. I don't mind the deflated tyre as I would have the compressor with me regardless and I don't mind the wheel on the roof except that it takes up a lot of room and uses up a lot of the allowable weight.

Anyway, deflating my stock tyre didn't make much difference if any to the size but it was sufficiently soft that I could push the rubber. Since my tyre already fit I couldn't really tell how easy it would be to push the rubber to fit something larger although I did think that if something was just a bit bigger it probably would fit (like 215/70/16). I'm not too sure about say 225/70/16 and I am not aware of anyone squeezing this in. This size is what got me wondering about how to fit it.

So... since I've used a belt to tighten and hold my rolled up tent to fit in the tent bag better I thought a similar thing could be done with a deflated tyre, but with some ratchet straps! I've included 3 photos. One photo shows some tic tacs sitting on top, and the other photo shows that after using the straps the tic tacs were able to pass through the space created. While the ratchet mechanism is a little bulky in my vehicle at least there is plenty of room at the top. It is just at the sides that there is very little room. I didn't go as tight as I possibly could but it must have been close.

I am not sure if being compressed like this has could have a negative effect on the side walls but I imagine that if it was only for a relatively short period of time there shouldn't be too many downsides if any. I plan to use my 16 inch wheels only when going up the beach or on some other off-road trip.

So, hopefully others might be able to make use of this technique as well! Hopefully I will be able to use it to fit whatever tyre I end up getting and will make a post in the coming weeks with a picture or two of the end result. I figure that with a 70 profile rather than my current 60 profile the sidewalls should compress better again so here's hoping!

Just an update... I have thought about things a little more and have tried a few variations on a theme.

First one was that while I had previously deflated the tyre as much as I could before applying the straps I hadn't released any more air after applying pressure with the straps. This time around I released more air after applying pressure with the straps and this then allowed me to tighten the straps which in turn allowed me to release more air etc. I ended up being able deflate the tyres a lot more than I had previously.

Second thing was that I experimented with 4 straps rather than 2. While I figured it would help with deflating the tyre more my main aim was to have the tyre change shape more uniformly. This did seem to be the case to some extent at least and it definitely did help release more air. Tightening one strap allowed me to release more air and then tighten another strap etc and it kept on going until I got to the point in the photos which seemed about right.

Thirdly, in my initial post I had returned the tyre to the spare wheel well with two straps, but this time I took three off and just left the tyre with one strap as it was less bulky. In my SJ model there is plenty of room at the front of the wheel well for at least two straps to be used without them hitting bodywork.

Anyway, I hope this might be of interest to you and I would be very interested to hear of anyone who gives this a go. At the moment I've only experimented on my spare tyre that already fits!

Also, I would be interested to hear from anyone as to whether you think that this could potentially damage the tyres in any way? If the tyres were old and brittle it probably wouldn't help them (although they perhaps should be replaced anyway) but maybe it could somehow hurt the steel belts of new tyres even? I pumped my tyre up again after removing the strap and it seemed to be perfectly ok. Even so, I would only ever consider using a spare like this for relatively short trips as it would re a 2nd set of wheels for offroad driving.

Thanks.

It really depends how long your going to leave the tyre in that condition.

Deforming the tyre from its natural shape is putting a load on those areas, just like leaving a flat tyre on the car for an extended period can stuff a tyre.

That's what I was thinking. It doesn't seem much different from having a flat tyre which could be plugged and driven on again. Also tyres at low pressure get deformed going over rocks and the like.

So I am thinking it is a good option for me as I only intend to use my 2nd set when going on a planned off-road trip. Hopefully I will have some tyres in the next few weeks so I will put a post in then.

Tyres have steel wires/belts around thier circumference to give them strength and shape. Obviously the belts are flexible so the tyre can flex/deform as it needs to in normal use. But i would be a little concerned doing what your doing and leaving it like that in the spare wheel well. As the spare could potentially sit there for years before it gets used. And then when you do use it again, it could be mishapen, causing vibrations. Or even dangerous and could potentially be a cause of de-lamination or ballooning or catastrophic failure when it does eventually get used.

I agree that it wouldn't make sense to leave term. In my case it would typically be only a few days at most as I would usually have my stock 17 inch wheel and tyre combination.

In the photos I went close to as far as I could just to experiment. It's possible I may not have to do at all up to 225/60/16 but assuming I do I am guessing I wouldn't have to apply as much force as I have done. I am only speculating for now though and once I get my lift and tyres I will know more.

I mean I am considering up to 225/70/16 with 215/70/16 being the other size.

Also, while I think of it, in my case at least I could have fairly easily released the straps once it was in the wheel well. Depending on the size of the wheel well compared to the larger tyre this would of course make it harder to remove the wheel and tyre. Maybe a little harder or maybe a lot. I am thinking that the 70 series profile will be easier to work with. There is only one way to find out so I will give it a try!

If it is a big problem. You could cut the well out and have a new larger well made from sheet metal in its place.

Funny you should mention that as my brother in law dropped round before and he is quite handy with things and he said much the same thing. At the moment I really don't know what I need to do since I don't have the tyres yet but at the moment I don't want to do anything that isn't easily reversible. The car is only 6 months old but I do plan on holding it for quite a few years so I might be open to more adventurous modifications in the years ahead.

Dropping in a new tyre well would be the best way to go but wouldn't be easy or cheap. It forms part of the rear crush zone so would need to be done well. There's also other things like fuel tanks & wiring to consider.

I think deflating & compressing the tyre like this will be ok as long as you don't have any sharp bends in the tread (leave out the tic tacs lol ). You're not leaving them in there permanently so I can't see it having any detrimental effect in just a few days.

Very clever idea!