Disco gearing with bigger tyres

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discomania

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My 90 has a 300tdi with a 44A R380 which is the higher geared of the two options and a Discovery transfer box.

I had 205 80 R16's on it and these were just too small really, I always thought the engine was a little noisy but I'd had huge off road tyres fitted before so it seemed worse than it was.

The circumference of 205 80's is 2307mm.

When I sold my Discovery I held on to two 6mm tread Michelin 4x4 tyres in 235 70 thinking they would be good on the Defender when I came to sorting my wheels out. I had fitted my winter tyres and piled up all my wheels and the two spare tyres and noticed that the 235's looked about exactly the same diameter as the 205's I'd just taken off. A quick look online reveals they are 2310mm in circumference so basically 3mm bigger! I know they are much wider and would offer better road grip and braking performance but I just don't think they will be big enough.

So I start thinking of standard size Defender tyres at 235 85 but I am concerned that my clutch will be under increased stress (used regularly on road and is not just a weekend toy) as this size of tyre is similar to my big off road tyres I run in the winter, and I do feel it takes a bit more to get her rolling with these on (the block like tread pattern doesn't help I know) also with these on she feels utterly powerless on hills I used to go up in 4th/5th gear no bother but now I see myself down in 3rd as the torque curve is sitting too low on these big tyres - I want hilly country road cruising!

I am for this reason now considering 245 70's which are 2354mm circumference which is a bit bigger, will be better than the 235 70's on the motorway for engine noise and not so big that getting her rolling will be tougher.

So thoughts, Disco boys on a Disco gear train might be able to answer this too, if any of you have say 235 85's or 245 70's installed, what is your Landy like on hills etc.
 
I had an early r/rover tfer box on mine, slightly higher ratio than the 1.2 disco one and run 33 inch tyres oh dear!, stuck std 1.4 def tfer box in much better, still a bit tall but I can live with it, whereas before pulling away up a steep hill was almost a non go
 
I think I will go for 245 70 R16's. Found some Goodyear ones. Might order them now and that will encourage me to get my wheels done.

The circumference of the tyres I have now are about 2530, I had 2307 so 245 70 16's will be 2354mm which is a little bigger but no where near the 2530 which I think is a big draggy on the clutch.
 
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