Really I have 37 inch tyres measured dia tyres. I had a 1.22 tranny box and 3.54:1 diffs and it was horrendus to drive. Feels really heavy Low range was god awful decending chaplegate 1st low. I decided after 2 minutes I'd be swapping my diffs out it was really really awful. I have 4.7:1 diffs now and 1.003:1 tranny box and its lovely in low box and high its spot on again. I wasn't getting into 5th gear on the motorway and if I did if it saw any small incline it would die off 65mph was a pita 4th too low 5th too high.
Wouldn't go back for anything!! only thing is the propshafts are spinning faster. For trialling in low 1st it just creeps along nicley high box it will sit at 65 bang on. I havent tried it towing yet but my 90 usually full of tools and will be towing a trials motor and hefty trailer with spares and tools. If its too high I'm half tempted to go to a 1.22 again but we shall see.