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Tire widths are apparently very subjective?

To: "'autox@autox.team.net'" <autox@autox.team.net>
Subject: Tire widths are apparently very subjective?
From: "Moore, John" <jmoore@spyglass.com>
Date: Fri, 21 Jul 2000 16:34:57 -0500
Apparently the stated tire width of a tire is very subjective. I've known
this for a while, but didnt realize by how much until I have been thinking
of going one size wider on front tires on my SE-R and found the following
listed in the manufacturers technical data:

                        195/50-15       treadwidth 7.2 inches i.e. 211.6 mm
Bridgestone RE-71       205/50-15       treadwidth 7.5 inches i.e. 220.5 mm
                        225/50-15       treadwidth 8.7 inches i.e. 255.7 mm

                        195/50-15       treadwidth 6.9 inches i.e. 205 mm

Dunlop SP 8000  205/50-15       treadwidth 6.9 inches i.e. 205 mm
                        225/50-15       treadwidht 8.1 inches i.e. 238 mm

                        195/50-15       treadwidth 6.3 inches i.e. 186 mm
Yokohama AVSi   205/50-15       treadwidth 6.7 inches i.e. 197 mm
                        225/50-15       treadwidth 7.9 inches i.e. 232 mm

>From this data, I would assume that going with a 205 RE-71 is almost going
as wide as a 225 from the other manufacturers. I would also assume that
RE-71's tend to run wide, as do most Dunlop SP 8000's. I would also assume
that Yokohama AVSi's run small. It does explain why my 195/50 RE-71's barely
fit the rear, while some other people I know of run 205/50 AVSi's with no
problem.

It sure does make it hard to figure out what tire size fits my car though.
Another oddity on some of these tires is also if you compare section width
to treadwidth. Some have a section width more than an inch wider than the
treadwidth, like the Dunlops. Some have as little as .3 of an inch
difference, like the RE-71's.

So has anyone found a magical formula for figuring all this out so that the
tires will fit, or is it still just a "best guess" game?

John Moore
 
1991 Nissan Sentra SE-R (STS)
1993 Toyota MR2 NA (CS)


"I dont want the statistics, just the truth!"


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