WHEEL SIZE STAGGER F/R older RSRs?

[Geneman]

Hello Peeps question.. On theses older RSRs, the wheels , and certainly tire sizes are huge in back compared to front. ( also hugely wider stance of course) did the cars actually use 2 diff size wheel diameters? say 15/16, or 16/17 f/r ? or is it just an illusion based upon the tired size> i love this look , as most of us do. can it be achieved on a LH NA carrera backdate just with flares and spacers ( and turbo arms)?

thanks frank

[Flieger]

935s used 19" rear wheels if I remember correctly.

[fredmeister]

Originally Posted by Flieger

935s used 19" rear wheels if I remember correctly.

Correct.
Porsches reasoning was that the rules limited tire width (which they were already at the limit) and to increase tire footprint Porsche increased wheel diameter while staying at the width limit.

So yes they ran different diameters as well.

[Bill Verburg]

Originally Posted by Geneman

Hello Peeps question.. On theses older RSRs, the wheels , and certainly tire sizes are huge in back compared to front. ( also hugely wider stance of course) did the cars actually use 2 diff size wheel diameters? say 15/16, or 16/17 f/r ? or is it just an illusion based upon the tired size> i love this look , as most of us do. can it be achieved on a LH NA carrera backdate just with flares and spacers ( and turbo arms)?

thanks frank

Not on the '73 2.8 RSR which ran 9&11 x15, not on the '74 3.0RSR which ran 10.5&12 x15

yes on the 935s which ran taller(19") rear tires to reduce the point loading and tire temps in the rear tire carcasses, similarly the latest 991RSR's are using 20s for the same reason

[Geneman]

thanks bill are you sayong that in the picture above ..the front and rear wheel diameters are the same? thats hard to believe.. is the tire size just so much bigger in rear (in tallness/aspect ..not width) that it looks like a bigger wheel, and hence thereally aggressive stance of the car? still confused thanks frank

[racer]

Whose to say, in the photo above, that those are factory "correct" sizes? Judging by the context and other cars in the pics, theres nothing to say that those wheels are not original, and nor are the tire sizes.

[Flieger]

That photo looks to have a good deal of fish-eye to it. Wide angle lenses shooting a car that isn't that close will do that. Exaggerated perspective makes the wheels look taller in the rear. It also makes the 911 look smooshed/shortend.

[michael lang]

If you haven't already seen it, I would suggest watching Moby and the Warhorse Gang. It is an incredible historical documentary of Porsche racing dominance in the 70's and especially the 80's. There is one segment that discusses just that one thing about wheel sizes and how Porsche used diameter to get around the width rules if the sanctioning bodies at that time. It's really long but totally worth the 4hrs or so of length.