[Spridgets] No real difference in tires

[Michael D Myers]

Frank,

175s are wider than 155s because that dimension is the widest part of the
tire in millimeters. The 70 or 80 is the aspect ratio, which is the
height above the bead as a percentage of the width, so the height of a
155/80 would be 155x0.8=124mm or 4.88 inches as you listed. The same goes
for the 175/70 which is 175x0.7=122.5 mm or 4.82 inches. But the width of
the 155 is 6.10 inches while the 175 is 6.90 inches. You can find a full
description of the info on a tire here:
http://www.goodyeartires.com/kyt/readingATire/

Mike Myers

On Wed, 09 Jan 2008 22:16:20 -0500 Frank Clarici <spritenut at comcast.net>
writes:
> Specification  Sidewall  Radius  Diameter  Circumference  Revs/Mile
> 
> 155/80-13      4.9in     11.4in    22.8in   71.5in        886
> 175/70-13      4.8in     11.3in    22.6in   71.1in        891
> 
> This is from a chart/calculator a lister sent me to check tire 
> sizes.
> Seems to me the 175/70s are a tad thinner and shorter than 155s.
> But I do have 175s on the 58 and they sure look wider than 155s.
> http://www.miata.net/cgi-bin/tirescgi
> -- 
> Frank Clarici
> Toms River, NJ