if we ignore the aspect of tyres for a second and just concentrate on wheels, if someone could give me thoughts on this id appreciate it.

the standard rz wheels are 17x8 et47 on the front and 17x8.5 et47 on the back

now looking at a stock body car, there currently is 43mm on the front and 42mm on the rear before going past the arches, this is off the most outer edge of the wheel(not the tyre)

now if you went to a et43 wheel, that means that those numbers are reduced to 39mm on the front and 38mm on the rear.

if you were to then change to a 10in wheel, thats increasing the rear wheel by 38.1mm in width, or add to 19.05mm to each end of the wheel.

That would take the rear wheel clearance down to 18.95mm

if you applied that to the front then thats 50.8mm increase in width or add 25.4mm to each end of the wheel.

that would take the front wheel clearance down to 13.6mm


Going off them figures, are they correct, the maths says they are but just wanted to check im correct first?

Ill come on to tyres next.....assume for this that all arches are a tight roll so ignore touching the outside arch

 

I'm not quite sure it I follow your numbers, but 18x10in all around will work... +50mm offset in the front is needed. Any less than that and you'll likely have to roll your fenders, any more and you'll likely rub the fender liner and/or shocks depending on your set-up.

In the rear there is more flexibility; +50mm to +38 should fit well without rolling the fenders.

 

thats very much moehler, im looking at a set of 19x10 et43 for all around, they are just my street wheels as i have a set of track wheels spare.

I was planning on rolling the fenders front and back anyway so sounds like they will work ok.

did i read somewhere your running 285s all around?

 

You should read the following thread if you are interested in maximum wheel and tire fitment on a stock fendered FD...

https://www.rx7club.com/suspension-wheels-tires-brakes-20/maximum-wheel-tire-width-fitment-guide-fd-892901/