i'm planning to order some wheels + tires within a few weeks; i've been thinking 19s, but i'd really like to do a 19/20" stagger, but with the same sidewall thickness front and rear (which makes the outer diameters more than the 3% difference they're allowed). the problem, from what i've read here and on roadfly, is the ASC won't work right because of the difference in outer diameters. but the first thing i do after i start the car is turn off the ASC. so my question is, if i run different outer diameters front and rear, will the car be driveable as long as ASC is turned off? or will it interfere w/ ABS and/or other crazy electronics i haven't yet discovered? (i'm not too concerned with how these wheels change the overall handling characteristics; i'll keep my current wheels in case the car sees any track time.)

It will be driveable if you turn the ASC off but I do not recommend it. Aside from the ASC you may also want to consider the front/rear brake bias it will create. IMHO, it will not be a safe vehicle to drive unless you do a brake upgrade with the F/R brake bias calculated in for the wheel sizes.

Just my 8 cents

point taken, i'll definitely keep that in mind. i did a bit more research and according to the miata tire calculator it'd only be a 3.8% difference in size (only 29 less revs per mile). i'll have to think about it a little more, maybe someone else has tried it or knows of someone who's done it?

as of now the plan is a 19 x 9.5/11" stagger using offsets similar to mk motorsport's 18" setup (they're the only company i've found to use those widths; i'll use their recommended ET5/21 or maybe a couple mms lower for a slight bit more aggressive stance...). anyone know of an 8er w/ 19 x 9.5 fronts? all the 19s i've seen are 8.5". i know the front suspension makes for a tight fit; i'd like to make sure it'll clear before i have the wheels built...

any other suggestions are welcome as always.

On a sidenote, I've got 18x8 + 18x9.5 with Pirelli P-Zero and they fit beautifully.

Make it extra safe and ad a LSD!

LSD is planned too. i just found some very useful info about using the optional 750iL LSD-- i thought i'd have to wait a while till i could afford one from an M5, but now i'll be able to get it from a junk yard. i've seen several V12 7s in j/yds, i didn't know i should've been checking them for a diff... probably could've found one by now... all you have to do is swap diff cover and input flange and the e32 unit is said to be a direct bolt-on.

back to the staggered diameter question, if my room mate's xk8 wheels are low enough offset to fit in the back of my car, i'll try driving around town w/ those and see if ABS acts up or if the whole braking characteristics in general are thrown off.

over the weekend i tried some wheels/tires that were 1" larger diameter than stock in the rear... and it drove fine, ASC and ABS weren't a problem at all, handling and brake feel didn't seem to change. looks like i'll be ordering up some 19s and 20s in the near future...

:redspot:redspot:redspot

With 19's and 20's the ASC will blink every now and then, Not very ofter though, That's the same set up I have with the car to the right, Good to know tht the asc is really on guard though.

i've been researching for a little while now and you're the first i've seen to actually try the 19/20 setup. what wheel sizes/offsets/tire sizes are you running? can i see some pics?

235-40----------285X30-----20mm off set.
http://img79.imageshack.us/img79/8849/bam0ff4.jpg