90 15" or 16" rims

Hi all
My 90 has 15" rims its had a disco 200tdi put in should I be running with 16" rims.
Will this make any difference to running costs on fuel or will the engine be running to high revs.
will 16" make him run better, not for cosmetic reasons just to help the engine and box.
Thanks for any help.

Rim diameter makes no difference to rolling circumference, which does affect gearing, check the tyre sizes.

Hi Paul D
My tyres are 235x75x15 do you think this size will be OK for the disco engine or as i've been told they are to small.
Thanks you your help.

Not really much difference between a Disco and Defender engine, but speeds and revs will also depend on the gearbox and transfer box as to the gearing it's running now. If all is standard then I'd have thought they're OK. I run 235 85 16, with my old Disco 300 tdi engine in a 1989 90, with the original gear and transfer boxes, but I'd say yours will rev a tad more than mine at the same road speed, but not by a fantastic amount, I feel that mine's slightly over-geared, but not much so I won't be changing it!

Thing with a Defender is that it _is_ essentially lower geared than most cars, so it's an eye opener if you drive one after 'normal' cars. If you changed to 235 75 16 tyres and wheels you'd feel the difference, but I dunno if for the better.

I do think, or seem to recall, that standard size is 235 85 16, or 750 16 ... which are virtually identical diameters!

That's quite small for a Defender. If you're using the Disco transfer box as well as the engine, it's got the higher 1.22 ratio to compensate. Sometimes people use 15" wheels on a Defender if they're doing a lot of offroading and want to use larger, fatter tyres. You generally find something a bit taller on a Defender - popular sizes include 235 x 85 and 265 x 75 on 16" wheels.

Paul D's beaten me to it.

Brown said:

Paul D's beaten me to it.

Click to expand...

Nice to see we both say much the same thing though ..

Thanks Paul D I think I'll go with the 16" just to be on the safe side.

Depends what you're doing with it. If you're making a lot of motorway journeys on the 15 x 235 x 75s it will probably seem a bit noisy (and thirsty). If it's just round town or country lanes it probably wont be too bad at all.

Thanks guys mostly motorways and about town I think as you say 235x85x16 will be better for me, as in july I am going from Hamilton to Yorkshire for my hols.
Thats a bit far on the 15s I'd guess. again thanks for the help.

That sounds like a good place to take a Land Rover. Lots of country lanes. Probably one of my favourite roads in the British Isles runs from Middleham in the East, up Coverdale and comes out at Kettlewell. Another of my favourites runs from Egton to Pickering. Just lovely countryside and a feeling that you're the only person about for miles.

I run mine on 235X85X16 a friend of mine runs on slightly smaller tires. Its surprising how many times he gets caught out with just that lit bit smaller tire height.