Tyre rolling circumference

[lhd]

Does anyone know, or can anyone point me to the difference in rolling circumference between standard syncro tyres and the 215/75/15 BF Goodrich tyres.
Rob.

[toomanytoys]

Standard?? what 185r14 or 205r14??? (both 80% ratio) 185s are 652mm diameter, 205's are 685mm.. (depending on brand)

Bigger diameter (therefore bigger rolling circumference)

[lhd]

Ok from what I can see the difference between a 185/80/14 and a 215/75/15 is around 52mm or 7.98%, will this have a significant difference in gearing or will it be bearable?
AAN box 1.9DG at the mo but looking at 1.9AAZ with the AAN box.
Rob.

[toomanytoys]

nearly 8% increase the DG wont pull it very well..
Whats the aan box got 4.86 final drive and a .85 4th?
My chunky (see the pic in the bashplate thread) 205/70r15's raise the gearing a bit much for comfortable driving.. its not bad once rolling, but does blunthe "performance"
Extra torque of the AAZ would of course help...

[lhd]

Your 205/70/15's seems to be a good compromise being the total difference is only 2.45%, where I have been looking recomends a sensible difference of +/- 2.5%.
What tyres are they? The tread does look quite aggressive though.
Rob.

[toomanytoys]

Blackstar Guyanes, french remoulds.. I avoid running on the road very far.. bit noisey.. but I find they are pretty good on tarmac, even in the wet.. they seem to be a lot bigger than the calculation says mind.. I'll stick a tape on one this weekend..
If I am honest, they are prob a little to aggressive in reality, unless mudplugging all the time.. dry and soft conditions good too, but slightly slick on top is where they dont work quite as well as they have very few edges to bite through and purchase on the harder stuff underneath..

Only problem with 205/70's is they dont come is as high load ratings generally. 97 being the max..