Replacement Tyre Sizes on a 120

Gary Stockton

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Hi all,

A quick question for those that know how this lot works ('coz I don't, really ... yet :x )

The 120 comes standard with 265/65x17 tyres on a 7J (I think) rim. No idea what, if any, offset that equates to - I think 0 ?

I put 265/70x17 Cooper STTs on as replacements - they fit perfectly, but the side lugs rubbed a bit on the front inner mudguard on full lock under compression (e.g. driving over the small bump going into my driveway). They also caught a little on the front mudflap after we trimmed it to fit the sliders - that's been fixed by cable tie-ing the sticky-out bit of the mudflap back to the body mount location :cool:

I solved the front rubbing by putting on 30mm spacers on all 4 corners - no more rubbing.

The tyres do the trick, and work well, but I suspect that after the 35mm suspension lift going in, on top of the 40mm body lift already there, that they're going to look a little lost in the wheel arches - the rear's already do.

So assuming I stick with Cooper STTs (which I most likely will do because I like them and they're not stupidly priced and do what they say on the tin), I plan to go up another size.

The current size gives me an OD of 802.8mm, or 31.6 inches. I can go to 285/70x17, which I think will fit OK, which give an OD of 830.8mm, or 32.7 inches.

I can also, for about £1.50 more each tyre, got to 33/12.5R17, which, clearly, is a 33 inch tyre. For quite a bit more I can go to 33x12.5R17 tyre - so up 2 inches but no wider.

So my questions are these:

  • Can I fit either the 285/70x17 or 33/70x17 without having to get new spacers or rims?
    Is there anything else I should consider (assuming they fit in the wheel arch etc. etc.?
    What are the issues (if any) around fitting the 35 inch tyres? (and remember, this is NOT a daily drive, but will be focussed towards overlanding and 'mild' laning :shifty: :whistle: so I'm not too concerned about changes in fuel consumption etc. )
    What, if anything, do I need to do to reset the speedo?
    What, if anything, do I need to do to the rear diff? :shock:
    What, if anything, do I need to tell my insurers? :roll:

Any thoughts / comments welcomed. The 35 inch tyres are significantly more expensive and will put too much stress on the drivetrain I suspect, so I've already mostly ruled them out - and they're getting into the 'stupid price' territory.

I've also thought about 'replaceability' in remote locations' which tends to rule out the 35 inch jobbies.

I'm leaning towards the 33/12.5R17, which are described as 'high-flotation' on the Cooper website - what the heck does that mean? They don't have quite the same load-rating as the 285/70x17, (which has the same as the 265/70x17). But maybe they're a bit more specialised and I should go with the 285/70x17's?? Sigh - decisions, decisions ... :think: :think:

Sorry for the long-winded posting :?
 

Jon Wildsmith

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Width is as much an issue as height when looking at tyre clearance. If you put a 12.5" wide tyre on you won't be able to go as tall as with a narrower size. I would aim for 285 width tops if 31.6" tyres with a 265 width rubbed without spacers. You might find even the 285x70x17's give you issues and need to look at something narrower.

I can't see a 35"x12.5" fitting on a 120 and still be able to go round corners without a lot of work BTW ;)
 

Graham

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Gary Stockton said:
The 120 comes standard with 265/65x17 tyres on a 7J (I think) rim. No idea what, if any, offset that equates to - I think 0 ?
Hi Gary,

I read some where that the standard Toyota rims are 30mm off set.

I seem to remember this because the black rims I have are 5mm offset, and this essentially pushes the wheels out 25mm.

STP80070.jpg

.
STP80086.jpg

.
black.jpg


I have since painted them all black.

As a foot note, I have just remover the black rims, which I think were 8J.

Graham
 

Graham

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Jon Wildsmith said:
I can't see a 35"x12.5" fitting on a 120 and still be able to go round corners without a lot of work BTW ;)
I have 35 x 12,5 x R15 on my recent 70 SWB.
When I stand the spare next to the BFG A/T 265 x 70 x R17 on my 120, the BFG A/T is totally dwarfed by the 35 inch.
I can never believe a 35 inch will go on a 120, without almost removing the wing :o
 
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Gary Stockton

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Looking at the 285/70R17 STT from Cooper, the recommended rim width is 7.5 - 9.5". I think the standard 120 rim is a 7" rim - will the tyres fit properly on a narrower rim, and would there be any inherent safety issues?

The 265/60R17 is specified for a 7 - 8.5" rim, and fit fine on the 120.

Cheers
 

Lorin

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No idea if I'm right but I'd worry that squeezing a wide tyre on to a narrow rim would cause the sidewall to bulge out more. If going overlanding that might be a real issue when running lower tyre pressures.
 

Jon Wildsmith

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I think Lorin is right, the narrower wheel will just give you a bit more side wall bulge but I'm not sure the 1/2" narrower than recommended will be a problem in the real world and 7" doesn't seem too unreasonable even if not ideal. Saying that, IIRC mr rubie got some 17" steels for the red car at a reasonable price so maybe that's the way forwards.
 

Gary Stockton

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quite like these from Arctic:



or


marginally different, 17 x 10 alloy

Would look good in black with 35" coopers :cool: :drool:

Bet they cost a bomb though :?
 
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