<VV> FC Tire pressure question

[Dale Dewald]

Hello,

At 19:47 10/25/2009 -0400, Bob Hall wrote:
>FCs have equal tire pressure front to back.They are trucks with different
>characteristics from the cars and do not need a different tire pressure
>front to  back.  Originally GM specified 24psi front AND rear.  I run 
>30psi all
>around on radials on my 64 Greenbrier and I have had no problems.

I do not want to create a controversy, but I took a look at the tire 
inflation information listed in the 1964 Corvair Owners Guide and the 1964 
Corvair Shop Manual Supplement.  Both references have the same table for 
the Corvair 95 series:

TIRE                      Cold F/R       Hot F/R
7.00-14 4-ply SP        24/30           28/35
7.00-14 6-ply SP        24/34           28/39
7.00-14 6-ply LT         24/45           28/50
7.00-14 8-ply LT         24/60           28/65

It is evident that GM specified a minimum 6-7psi pressure differential 
depending on the tire construction--not as much as the cars--but still 
significant.

As I mentioned in my previous tire message, we really have no modern 14" 
replacements for the 4-ply and 6-ply SP (special purpose reinforced 
sidewall) tires that were originally fitted on FCs. The closest match I can 
find to the original type tire [but on a 15" wheel] is the 205/70R15XL with 
a load index of 100.  For the stock 14X5 wheel, however, there are several 
brands of 185R14 or 195R14 6-ply and 8-ply LT tires available which are 
direct replacements.

If you wish to use the P205/75R14 standard load index 95 passenger car 
tires be aware that they are likely to be overloaded in certain 
situations.  Therefore I would recommend inflating them to the full 
sidewall listed pressure [35 or 44psi depending on manufacturer] for the 
rear and about 5 psi less on the front.  This is essentially what GM did 
for the base 4-ply tire.

Dale Dewald
Hancock, MI