Start by reading the owners handbook or the load section in the service manual.
The heaviest design GVW for a KA10 pickup is 5600lb.
The maximum front axle weight is 2900lb.
The maximum rear axle weight is 3221lb.
Now divide the heaviest axle by two and you will see that the minimum single wheel/tire load rating needs to meet or exceed 1610.5lb.
So a 2200lb rating gives nearly a 400lb per corner safety margin.
However it does not raise the capacity of your truck!
The published curb weight of a KE10 LWB without options is 4221lb.
This gives you about 1380lb for passengers,cargo and again any options.
Be aware some options are heavy, A/C and a step bumper are about 200lbs!
The factory service and overhaul manuals can be downloaded (usable copies) here.
http://67-72chevytrucks.com/vboard/s...d.php?t=558016
An owners handbook can be bought from nearly any vendor if you don't have one.