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BarryJB BarryJB is offline
Uno Dei Molti Porschisti
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Join Date: Feb 2004
Location: Elfin Forest, CA
Posts: 332
I think only a few versions/colors of older cars look right with any of the candidate 18's - your slant-nose probably one of them, Chris. But I don't think those new Porsche 18-in Fuchs will fit our older cars at all, if that's the desired esthetic, so it's Alton/Zuffenhause 17's or of course made-up 17-in wheels using old 16-in centers. Or I guess one could get 18in rims made up the same way... might not look so hot though.

I don't think 245s are much trouble to get... but no way I'm going backwards from my 265s!

But the rationale for going from 16 to 18 is undeniable.

Re possibilities, Timmins' Instant-g original detailed wheel fitment page was very helpful, however it looks like he may have replaced it (or I just didn't look hard enough) with a "Tire Diameters for Common Porsche Fitments" page which instead offers a quick reference for many of the outer tire diameters from 185/75-14 through 335/30-18.

Alternatively, there's a handy tire-diameter calculator on a Miata forum at Tire size calculator that also lets you compare two tire/wheel combos re diameter and effect on speedo.

Using that, the diameter of a 225/50-16 is 24.9in; a 245/50-16 is 25.6in; 3.2% increase; with 245 when speedo reads 60, you are doing 61.9... going to a 265/45-26 is actually less of an increase at 2.1% - 25.4in, at 60 you are doing 61.3.

Decisions, decisions...
85 Carrera Coupe, OBD-I 993 3.6 conversion w/(ever-increasing list of mods)óclosing in on 425,000 miles. So far, 100,000 on the 3.6. Mad Wasp (Benelli TnT 1130).

Last edited by BarryJB; 06-08-2013 at 09:13 AM.. Reason: typo
Old 06-08-2013, 09:11 AM
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