<VV> Tires

[BobHelt@aol.com]

In a message dated 1/7/05 10:13:29 AM US Mountain Standard Time, 
bwschug@charter.net writes:

> You know as well as I do that revs/mi varies quite a bit among tires 
> because of variances in size and construction. I have never seen any 
> revs/mi figures for actual 6.50-13 tires. Where did you get the 864 
> figure? Is this a Chevrolet spec? If so, you know it's just a spec, not 
> a figure from an actual tire.
> 
Hi Bruce,
First I want to thank you for your detailled response. I think that we often 
suffer from trying to compare apples and oranges. 

As far as the size of replacement tires is concerned, revs per mile are 
generally the criterion for making this choice. And the revs per mile are usually 
stated in the form of a specification. This spec is a goal or target for tire 
design and manufacture. Sure some tires may not meet the spec but if they are 
outside the spec, then they must be considered rejects. Probably every product 
manufactured in the US, is defined by a set of specifications, that are the 
requirements, that product must meet. If the product is outside the specs, it is 
subject to rejection. Tires are the same.

As for the two-ply 6.50X13 tires used on the 1962-65 Corvairs, the spec of 
864 comes from the Chevrolet (Corvair) specifications document published by GM 
for each year. The number 863 is for the Yokohama Agis 175/80R13 tire published 
on the web page. This makes the Agis tire a direct replacement for the 
Corvair tire per this specification. I personally would not want to use any tires 
that don't meet the manufacturer's specifications. 

Now if you want to use a larger size tire, that is the consumer's choice. And 
for the Corvair, the 185/80R13 is a good choice. But be aware that by 
choosing to exceed the tire manufacturer's recommendations, you are taking on the 
responsibility for doing so. The 185/80R13 is a safe choice, but where does it 
stop? If you mount tractor tires on your Corvair and have an accident resulting 
from the tires, who is to blame, the tire company? Who is to blame if you put 
larger tires on your car and get a speeding ticket because you were going 
faster than you thought?

Regards,
Bob Helt