Chevrolet 10 Series 1968, Service Manual, Page: 559 / 713

WHEELS AND TIRES 10-8
TIRE USAGE AND INFLATION PRESSURE TABLE
Gross Vehicle Weight
or Max. Load Capacity
(Incl. Passengers)
Tire Size Tire Ply
Inflation
psi
Front
Pressures
(Cool)
Rear
G10 CHEVY VAN (90 & 108 INCH WHEELBASE)
3900 lbs.
Passenger Type Tire
6.95 x 14 (Std.) 4 ply rating—2 ply 32 32
4500 lbs. 7.35 x 14 (Opt.)
8 ply rating—4 ply 32 36
Truck Type Tire
4500 lbs. 7.00 x 14 (Opt.) 6 ply rating 35 45
5000 lbs. 7.00 x 14 (Opt.) 8 ply rating 35 55
G20 CHEVY VAN (108 INCH WHEELBASE)
Passenger Type Tire
5200 lbs.
7.75 x 15 (Std.) 8 ply rating 28 36
5800 lbs.
8.15 x 15 (Opt.) 8 ply rating 28 36
Truck Type Tire
6200 lbs. 8
x 16.5 (Opt.) 6 ply rating 35 45
G10 SPORTVAN (90 & 108 INCH WHEELBASE)
1 to 5 Pass. (2 Seat)
+300 lbs. Cargo or
1 to 8 Pass. (3 Seat)
(1200 lbs. load)
7.35-14 8 ply rating—4 ply 32
36
G20 SPORTVAN (108 INCH WHEELBASE)
1 to 5 Pass. (2 Seat)
+650 lbs. Cargo or
1 to 8 Pass. (3 Seat)
+200 lbs. Cargo
(1400 lbs. load)
7.75-15 8 ply rating—4 ply 28 36
1 to 5 Pass. (2 Seat)
+1250 lbs. Cargo
1 to 8 Pass. (3 Seat)
+800 lbs. Cargo
(2000 lbs. load)
8.15-15 8 ply rating—4 ply 28 36
1. Tire inflation pressures may increase as much as
six ( 6 ) pounds per square inch (psi) when hot.
2. For continuous high speed operation (over 75 MPH)
increase tire inflation pressures 4 pounds per square
inch over the recommended pressures up to a max­
imum of 32 pounds per square inch cool for 4 ply
rating tires, or 40 pounds per square inch cool for
8 ply rating tires. When the 4 psi pressure adjustment
for sustained high speed with maximum vehicle load
would require inflation pressures above the maximum
allowable, speed must be limited to 75 miles per hour.
3. Cool tire inflation pressure: after vehicle has been
inoperative for three (3) hours or more or driven less
than one (1) mile. Hot tire inflation pressure after
vehicle has been driven ten (
10
) miles or more at
60-70 MPH.
4. Vehicles with luggage racks do not have a vehicle
load limit greater than that specified.
5. When towing trailers, the allowable passenger and
cargo load must be reduced by an amount equal to the
trailer tongue load on the trailer hitch.
6 . When optional truck type tires are used on Sportvan
Vehicles refer to Chevy Van GVW ratings above for
proper tire inflation pressures.
SERVICE OPERATIONS
Wheel Nut Torques
On all vehicles equipped with disc or cast spoke
wheels, it will be necessary to retorque the wheel nuts
at first 1000 miles and every 6000 miles thereafter. See
Specifications for correct nut torques.
Correcting Irregular Tire Wear
Heel and Toe Wear--This is a saw-toothed effect where
one end of each tread block is worn more than the other.
The end that wears is the one that first grips the road
when the brakes are applied.
Heel and toe wear is less noticeable on rear tires than
on front tires, because the propelling action of the rear
wheels creates a force which tends to wear the opposite
end of the tread blocks. The two forces, propelling and
braking, make for more even wear of the rear tires,
whereas only the braking forces act on the front wheels,
and the saw-tooth effect is more noticeable.
A certain amount of heel and toe wear is normal. Ex­
cessive wear is usally due to high speed driving and ex­
cessive use of brakes. The best remedy, in addition to
cautioning the owner on his driving habits, is to inter­
change tires regularly.
Side Wear— This may be caused by incorrect wheel
camber, underinflation, high cambered roads or by taking
corners at too high a rate of speed.
The first two causes are the most common. Camber
wear can be readily identified because it occurs only on
CHEVROLET TRUCK SERVICE MANUAL