2002 Defender TD5 - what tacho to use?

What size tyres? I assuming 235/85/16's

I've only seen the VDO 52mm tachos in 4000 and 7000 rpm.
I have the 4000 version in my county.

Steve

I don't want to sound like a salesman but I have a working VDO Vision 80mm tacho that I JUST removed. It has a mount that fits on top of the dash. I removed it as I did not feel the need for one and I am trying to remove as much as I can.