Stupid newbie question on spare wheel size...

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Hard-Drive

Hard-Drive

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My Defender came with standard size road tyres on modulars (which it's on) and some off road 265 75 R16 Insa Turbo Tractions on alloys. I only have four alloys.

My old Disco was a similar story came with the standard road tyres, but I ran it on 265 75 R16 off road tyres too for all of it's life, and if I'm honest it did dent the performance a bit, especially up hills on motorways towing.

I want to try the Defender on the Insa Turbos, but I don't have a spare. I don't want to buy a spare until I've convinced myself I'm happy with the bigger tyres by doing some miles first. I'm hoping it will be OK, it seems to have a lot of grunt compared to my old Disco, and obviously a lower transfer box ratio.

My question is this...in the event of a puncture, as a "get me home" measure, is is OK to run one smaller tyre? I've thought about it and I've convinced myself that as long as the diff lock isn't engaged it should be fine, but if there's a definitive answer, please let me know.

As an aside, the Disco needed a "Camel Cut" to the rear arches otherwise it would foul the bodywork on full articulation. Will the big tyres be ok on my 110 as is?
 
Hard-Drive said:
My Defender came with standard size road tyres on modulars (which it's on) and some off road 265 75 R16 Insa Turbo Tractions on alloys. I only have four alloys.

My old Disco was a similar story came with the standard road tyres, but I ran it on 265 75 R16 off road tyres too for all of it's life, and if I'm honest it did dent the performance a bit, especially up hills on motorways towing.

I want to try the Defender on the Insa Turbos, but I don't have a spare. I don't want to buy a spare until I've convinced myself I'm happy with the bigger tyres by doing some miles first. I'm hoping it will be OK, it seems to have a lot of grunt compared to my old Disco, and obviously a lower transfer box ratio.

My question is this...in the event of a puncture, as a "get me home" measure, is is OK to run one smaller tyre? I've thought about it and I've convinced myself that as long as the diff lock isn't engaged it should be fine, but if there's a definitive answer, please let me know.

As an aside, the Disco needed a "Camel Cut" to the rear arches otherwise it would foul the bodywork on full articulation. Will the big tyres be ok on my 110 as is?
Click to expand...

What tyre and wheel size is the spare you intend to run with a 265 75 16s?
 
I run 265/75/16 insa turbo special tracks on my 90' i have 4 modulars, and an old
Disco rim with a slightly smaller tyre, ( cant give u exact size as vehicle is on the ramp in the workshop )

However mine drove home 20mikes with a puncture without any issues.

Mine hits the radius arms on full lock, you can alter the stops to prevent this, however i choose not too, sometimes need the extra lock when out in the dark round the farm, and also i run a different set of wheels and tyres in the summer, that dont hit.

Trust me you will know if they touch, just ease the lock a touch and the noise stops.
 
On my Defender 90 there is plenty of room for 265 x 75 x 16 tyres in the arches on standard height suspension and standard wheelarch extensions. You could probably get 285 x 75s in there without any modification I would guess.

You see a lot of other cars with small space saver spares these days, which usually have a speed restriction on them as they're narrower and often a smaller diameter than the standard tyre. If you were to have an accident with ill-matched tyres on, and it turned out not to be a manufacturer-approved option however, you could be in trouble!
 
Nice one guys, thanks for the replies so far.

I just want to check though, in the event of a puncture and I have to run three 265/75/16s with one 235/86/16, on tarmac, it won't damage the transmission due to the different sizes, correct?
 
That stuff really wouldn't have helped the one time I've punctured a Landy tyre (ripped a sidewall).
So is it OK to run a smaller spare in an emergency without transmission damage?
 
In the short term it probably won't accelerate the wear. After all a lot of people drive around with those space saver spares on for a while. One of my neighbours has been commuting to work on his for a week or so now, and its on his driving axle. Provided the movement in the diffs isn't too excessive it's unlikely to kill them. The concern arises because the gears in the diff aren't like, say, the gearbox with its roller or ball bearing races, they're just plain bearings, so a lot of movement could cause wear.
 
Last edited:
Would certainly get you home ok.

Tyre foam is ok for punctures but a split sidewall is game over and a relay home or a tyre van on the side of the road. ( not cheap)

So best to carry a spare whatever the size even if it only gets you to the local tyre factor. Or carry both tyre foam and a spare.
On the farm we have a plug kit which you can do with the tyre still on the rim and the vehicle , however it was not cheap and you need a cordless drill, so a bit over kill for general use. Might be a good plan if on a big overland expedition.

If anyone is interested i will get the make and post a pic
 
cowasaki said:
Are you talking about a different circumference of tyre as a spare? If so then I wouldn't risk it as you are likely to destroy the diff!
Click to expand...

Yes I am, two different sizes. I might be wrong here but surely all that will happen is that the small wheel will rotate faster than the bigger one, but as that's what's a diff is designed to do it shouldn't matter? It's no different to driving round a corner surely?

I thought it would only become an issue if the centre diff was locked?

...but I might be totally wrong!
 
Hard-Drive said:
Yes I am, two different sizes. I might be wrong here but surely all that will happen is that the small wheel will rotate faster than the bigger one, but as that's what's a diff is designed to do it shouldn't matter? It's no different to driving round a corner surely?

I thought it would only become an issue if the centre diff was locked?

...but I might be totally wrong!
Click to expand...
you can use a smaller wheel as a get you home ,the car would have unequal grip for severe handling or braking which would effect insurance if caught , rear diff will turn more,so will wear out quicker, center diff wont be effected locked or not
 
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