larger tyres +ratios?

Hi
Was wondering a few bits about larger tyres.
At what size are ratios needed to be alterted? why are do they need to be? will 265/16s need any alterations? and lastly How do you change the ratios, is it in the diff or gear box?

got 35/10.50/16 simex i aint changed nothing..i dont go above 50mph so i aint worried about ratios.

I've got 265's on mine with standard T/F box and diffs.
The gearing seems a little tall in 5th and I often have to change down to 4th on hills.
Speedo reads about 5mph low between 40 and 70.
Other than that, it's fine.

I've got 35's on mine and have no probs with ratio's (except the speedo is about -10mph out now).

It's a 200tdi.

That said I have a standard 1.4 defender transfer box so not sure how it would pull if I changed it for a 1.2 disco unit.

The transfer box is where you would change your ratio's really although I guess you could fit series diffs if you wanted to go lower?

Someone on here will know for sure.

235/85 and 265/75 should not make a noticable difference, as both are replacement for 750r16 , whenyou get to 255/85 and 285/75 then if you need to you make a ratio change in transfer box , ashcroft site gives you the various ratios available HTSH

Cheers people. thats great help. all in the tf box.
how do you know what tf box is set to what ratios?
also i am guessing a 1:4 def tf box = to 1 rev of the crank gets you 4 turns of the tf box? High ratio,yes? and the 1:2 is obviously a lower ratio.
I see many thanks

I run on 305/45/22 tyres with a 1:222 Transfer box. Speedo is 100% accurate as measured against my GPS speed. Engine spins at just under 2,500 RPM for a true 70Mph. Oh, and this is on lowered JE Engineering suspension. Had to modify the rear wheel arch trims a bit to allow sufficient wheel travel without rubbing. (Hot air gun). No problems with MOT.

Gnubees said:

I run on 305/45/22 tyres with a 1:222 Transfer box. Speedo is 100% accurate as measured against my GPS speed. Engine spins at just under 2,500 RPM for a true 70Mph. Oh, and this is on lowered JE Engineering suspension. Had to modify the rear wheel arch trims a bit to allow sufficient wheel travel without rubbing. (Hot air gun). No problems with MOT.

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take it the landy never goes offroad then:doh:
why would you lower a 90? thats like gettin an evo9 and raising the suspension,its just wrong.
:emps1:

wiltshire landyman said:

take it the landy never goes offroad then:doh:
why would you lower a 90? thats like gettin an evo9 and raising the suspension,its just wrong.
:emps1:

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Just getting an evo is plain wrong

redhand said:

Just getting an evo is plain wrong

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true but not as wrong as lowering a 90 and sticking big chav wheels on it

Gnubees, FFS Why ???? that is just so wrong

lol I totall agree with the lowering of a defender, it is somehow wrong, almost like wearing wellies to bondai beach.
But i know you'll hate me for saying this, i saw a lowered 90 yesterday round dorchester, in black and it did make a refreshing change to a naff corsa! It actually looked quite good.
Anyways matey is from 'landan' not many green lanes there!

well im running 37/36 inch tyres and a disco 1.2 transfer box and it horrendus. I am going over to 4.7ratio diffs and mabe upping the transfer box to 1.0 so my low range is usable once again.

New here but I have to agree, never lower only raise. However why not have a landy and an Evo, fun on two levels!!

well put.
Cant help but think that people who own evo's and imprest-her's are a little..er..****!
My old boss had one and he was a knob in fact he had both evo and impretza and he'd spent graands on the engine only for it to blow up!..lol..little winkie man!!

well put.
Cant help but think that people who own evo's and imprest-her's are a little..er..****!
My old boss had one and he was a knob in fact he had both evo and impretza and he'd spent graands on the engine only for it to blow up!..lol..little winkie man!!

my 90 is on gas shocks and i drive around on the roads with it dropped, much better handling, soon as i get to work/field/lane i raise it up, i reckon it looks quite smart when its low, obviously not much use off road though