Gearing on my Defender

Hi all

Been searching high and low and haven't found an answer

Basically, I have put a 1.2 (Discovery) ratio transfer box in my Defender 90, with 265/75 R16 tyres and it pulls fine, exept it doesn't like 30mph in 4th and with all the hills around where I live I'm constantly between 4th and 5th between 40mph and 50mph. I've decided to put my old 1.4 (Defender) ratio box back in.
I've been planning on putting 285/75 R16 tyres on soon so I was wondering if anybody knows if it will take it up to the gearing I've got now, seeing as the wheels are 1" taller give or take. I highly doubt it but I've been very wrong many times before.

Basically in a nutshell, does anyone know which is taller gearing

265/75 R16 (32" ish) - 1.2 Discovery box
or
285/75 R16 (33" ish) - 1.4 Defender box

Any advice is greatly appreciated

Thanks Dave

Try this Ashcroft Transmissions - Ratio Calculator

Kwakerman said:

Try this Ashcroft Transmissions - Ratio Calculator

Click to expand...

That perfect, thanks very much, according to this the defender transfer box with 285 tyres is about 200rpm higher, so it shouldn't struggle in 4th, Cheers