Wheel spacers, doesn't make sense??? Options

[retrotech]

Help.
I have been on this topic prior to fitting wheels, but the numbers don't make sense. I am using 17 x 7" 993 wheels with marked off set of 55mm. I have 205 tires mounted. I want to use 215, but everyone says they won't fit.
From the beginning I thought I would need 23mm spacers, but I just tried some 1/4" spacers that were laying around and they work.
On the front with 1/4" there is slight rub on full lock, at front of tire, with 1/2" none.
On the rear with 1/4" there is a closer fit 1/4 - 3/8" at the top inside, with tons by the fender lip, that has been rolled.
With 1/2", just the reverse as above. It almost looks like I could use 215's. But how can this work with only 1/4 & 1/2" spacers.
Anyone with a similar application to advise on there spacer size?

Retro

[Mueller]

55mm - 6.5mm = 48.5mm which is approx. what the 15x7 "R" rims are...(49mm I believe)

35mm offset (for a 7" rim) is what Revolution sells which fits under the stock fender.

the front can take a rim with less offset, that is why the 12.7mm spacer works better....you could get away with an even thicker spacer in the front if you want to.....

23mm is not the correct offset for 7" wide rims under stock fenders

for comparison, when I had the "ricer" rims mounted to my car, they have a 40mm offset and with a 205 tire, they fit perfect in the rear

[retrotech]

Mueller,

Thanks for your reply. If the Rev. wheel is 35mm & your rims are 40mm, doesn't that mean a 55mm wheel should have a 15 - 20mm spacer? How can mine work with a 12.7mm/1/2" or even a 1/4" 6mm?
I thought stock 911 wheel was 35mm, so that works out to 20 mm spacer? I was ready to buy 15mm on E Bay, when I discovered that would push them out too far. What am I missing here? Will a 215 tire fit?

[Mueller]

the 215's might fit, it's different car to car and even tire to tire....

there might be a 225 tire that'll work, but if you change brands down the road, you might have problems.

regular 911 15x7's have a 23mm offset, these do not fit a bone stock fendered car in the rear.............

how is the clearance on the inside of the car near the trunk wall and trailing arm?? the 1/4" spacer might be too small and you might rub when hitting bumps.

without looking at your car, it's hard to tell if your fenders are truely stock with just a little bit of fender lip rolling....someone might have "pulled" on them enough to still look stock, yet not be......

any spacer wider than 20mm is going to be too wide, on a bone stock fender

you need to go to Tire Rack . com and look at the dimensions of tires you are interested in, they must be the correct size and brand, tires vary too much brand to brand...don't look at 15" tire comparison, only look at the 17" tires