
Originally Posted by
Sleepy
My understanding (and happy to be corrected

) the older sizes are 100% profile (aspect ratio). So 7.50 has a tread 7.50" and sidewall 7.50". So the diameter is 16+7.5+7.5 = 31"
Therefore the 7.00 and smaller would have correspondingly smaller diameter.
I dont think the format matters - although "R" indicates radial.
Tyres do vary a bit and if critical take a tape measure.
ish
I think the nominal total diameter of the 7.50/16 (however spelled and radial or bias ply) is 32 inches. But the smaller numbers are smaller in every direction. Most people wouldn't notice the smaller diameter of a 7.00 bar tread BUT you really don't want a bar tread for their look on a car used as a daily driver. Bar treads are for heavy-duty mud work - tractor work.
Series Land Rover speedos are not accurate except by extreme good fortune. Just learn the error and adjust your driving accordingly. After 5 speedos in 4 cars, I have had only one exactly correct.
The 7.50 tyres, or the 235/85, are the ones you want, in a tread which is functional on-road even if you want an off-road look (and/or function). Unless you plan to do mostly off-road and rarely highway driving, go for a radial construction.
Steve
2003 Discovery 2a
In better care:
1992 Defender
1963 Series IIa Ambulance
1977 Series III Ex-Army
1988 County V8
1981 V8 Series 3 "Stage 1"
REMLR No. 215
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