Wheel/Tire help?

[tschall]

Stupid is as stupid does, experts weigh in. The car in question is an '86 911 M491. Current set up: Kinesis F19 9 & 12, front and rear. New set up Moriani Italian Fuchs clones. 17", Front 8, rear 10". Matt says, 8x17s ET +10,6 and 9x17s ET +15, designed for fitment to your car with factory spacers. What are factory Spacers/offsets sizes? Anybody have definitive recommendations? Car has current spacers/adapters(centric) on each wheel/axle respectively different. Next question is tire recommendations? Size(s)? Current set up is front wheel height installed 24 & 3/8", rear 24 & 5/8". All assistance appreciated. Education is sorely needed.

[Bill Verburg]

Originally Posted by tschall

Stupid is as stupid does, experts weigh in. The car in question is an '86 911 M491. Current set up: Kinesis F19 9 & 12, front and rear. New set up Moriani Italian Fuchs clones. 17", Front 8, rear 10". Matt says, 8x17s ET +10,6 and 9x17s ET +15, designed for fitment to your car with factory spacers. What are factory Spacers/offsets sizes? Anybody have definitive recommendations? Car has current spacers/adapters(centric) on each wheel/axle respectively different. Next question is tire recommendations? Size(s)? Current set up is front wheel height installed 24 & 3/8", rear 24 & 5/8". All assistance appreciated. Education is sorely needed.

for M491
front: There is a 21mm spacer built in to the front hubs, stock Fuchs fitment would have been 7ET23.3 x16 w/ 205/55 tire an8ET10.6 in that position will have the outer lip 1" further out than the 7ET23.3 An 8ET10.6 x17 will have the lip a tad further out only because the lip width of a Fuchs is ~.3" narrower than the lip width of most modern wheels(BBS is an exception here)

rear: In back the spacer is a separate part 930.331.611.04 and is 28mm thick on '78 up cars, earlier cars used a different 54mm spacer, '78 -85 used 8ET10.6 w/225/50 x16 '86 -89 used 9ET15 w/ 245/45 x16 tires

so if you keep the spacers and want 17ss, 8ET30puts the front wheel lip a tad more out than a stock 7, for every mm reduction in ET the lip moves an additional mm more out

in back similar math applies

most people who go to bigger wheels want to remove the spacers in front you can't but in back you can and that changes the math

also most want wider wheels and tires
8.5 - 9 front and 10-11 rear is most common, this also changes the wheel specs

when changing wheels I always urge to choose the tires first then wheels to place the tires for best fit.