[alfa] Formula for calculating correct tire size

[alfacybersite <acs@xxxxxxxxxxxxxxxxx>]

Read Jeff Greenfield's post first. Yeah, I thought S and SR sure looked 
like speed ratings. I also figured the original sidewall height of the 
'69 Spider's sidewall was probably 70. If that is the case, how come the 
calculator gives 23.09" diameter for a 165/70-14 (presumably new) tire 
and the well used 165/SR-14 tire I have measures 24"? Or are these 
measurements purely arbitrary and one manufacturer says, "Hey, let's 
make our 165/?-14 tire 1" taller than our main competitors?" What owner 
ever knew if he had a 70, 78,  80 (or?) series tire in the "good old days"?

Biba
Irwindale, CA USA
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