<VV> Tire Pressures for 15" Tires - and Other Sizes

[Dale Dewald]

At 20:27 9/30/2009 -0400, Hank <kaczmarek at charter.net> wrote:

>Another question for LM owners with 15X7 Camaro rims.
>
>My tires are on the way from Tire Rack. I got 205/60/15 BFG  Traction T/A's
>
>Great price on the tires. With Road Hazard they ran 268.42 with shipping 
>included.

I got a similarly great deal on the same tires in 195/70R14 size for my 
wife's '65 Monza.  We have been extremely happy with them.

>Any opinions on Air Pressures F/R?

I ran 205/60R15 Pirelli's on our '65 Corsa for many years.  They were H 
speed rated and had a specified maximum inflation pressure of 44 psi at 
full load.  Using the load capacity and maximum inflation pressure 
specifications of the original 6.50-13 and 7.00-13, I came up with F/R 
inflation pressures of 27/40 psi as a starting point.  After running 
driving the car a bit I settled upon 28/41 psi.  I got even wear on these 
tires both front and rear--with a mix of highway driving, trips around town 
and autocrossing.  They ended up dry rotting before wearing out.

I strongly suggest taking into account the rated maximum inflation pressure 
(check the sidewall !!) when figuring the inflation pressures to 
use.  Compare this to the pressure/load ratings of the stock tires and the 
manufacturers suggested pressure and do some proportional calculations.

Example:  I have fitted oversize 315/70R17 flotation type load range D 
(3195lbs at 50psi max) tires on my 2001 Dodge 2500HD 4X4 diesel truck. The 
stock tires were 245/75R16 load range E (3042lbs at 80 psi max).  The owner's 
manual specifies 70/80 psi if the truck is used for maximum payload carried 
in the bed, but specifies front tire pressure increased to 80 psi if the 
truck is fitted with a snow plow.  Do I put 80 psi in my 50 psi rated 
tires?  Of course not, I use proportionally lower pressures tailored to the 
load and inflation ratings of the these specific tires, typically 50/44 F/R 
in the winter.  The same logic applies to modern radial tires which are 
designed for much higher inflation pressures than the bias ply tires 
originally fitted to our Corvairs.

BTW, the H-rated BFG Traction T/A (rated 44psi) tires on my wife's Monza 
are currently inflated 28/41 psi F/R.

Dale Dewald
Hancock, MI