measuring FLUSHNESS -
First get a big level (one that's actually level is best).
Second, get an accurate tape measurer (mm is good), preferably one that hasn't been used for real work since they get bent an inaccurate for precision measuring quickly.
If you have calipers instead of a tape measurer, even better.
A second "bullet" level is good to make sure your measuring device (tape or caliper) is level as well.
I didn't use a bullet. only 2 hands and taking pics is a pita without help. :'(
Step 1:
Park on level ground.
Step 2:
get the level against the fender and level. be sure to check the top and bottom levels if you want accuracy.
Step 3:
measure the distance from the outermost edge of the wheel to the level.
Here's some pics if you still don't get it:
The measurement from the stock wheels on my truck is 38mm from flush on the front fenders. It's more in back, but I don't recall the number and it doesn't matter for this example. Why did I just type that then ....... because I'm rambling? My factory wheels are 8 +30 (diameter doesn't matter here). so, to get this width wheel flush, just subtract 38mm from the current offset which would result in 8" wide with a -8 offset. plug your wheel numbers into the offset calculator to get other widths flush. a 9" width would be flush for me up front with a +12 offset.
These numbers aren't relevant for the mr2, but the concept is exactly the same for any vehicle.