Chevrolet 1980 Light Duty Truck Service Manual page 306

3E-4 WHEELS AND TIRES
WHEEL USAGE AND TIRE LOAD LIMITS (LBS) AT VARIOUS INFLATION PRESSURES
Wheel Tire
Code Size
ZJ
9.50-16.5
ZJ
9.50-16.5
Z X 7.00-16
ZX 7.50-16
Z X 7.50-16
z w 8.75-16.5
z w 8.75-16.5
WHEEL CODE AND LIMITS
W heel Limits
Size of Max.
Code
W heel Load
(Lbs.)
15 x 7 JJ
CF, BU 1670
15 x 8 JJ 1910
BT, CK
15 x 8 JJ 1760
CH
15 x 6 JJ 1670
CB
16.5 x 6.00 2680
ZW
15 x 6 JJ 1670
CB
16 x 5 K 1800
ZR
15 x 6 JJ 1670
CC
16 x 5 K 1800
ZD
19.5 x 6.00 2540
ZY
15 x 8 J J 2030
BW, ZC
CORRECTING IRREGULAR TIRE W EAR
Heel and Toe W ear
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.
Excessive wear is usually due to high speed driving and
excessive use of brakes. The best remedy, in addition to
cautioning the owner on his driving habits, is to interchange
tires regularly.
Side W ear
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 radily identified because it
occurs only on one side of the treads, whereas underinflation
causes wear on both sides. Camber wear requires correction
of the camber first and then interchanging tires. There is,
of course, no correction for high cambered roads. Cornering
BIAS LIGHT TRUCK (LT) TIRES
Load
Range 30 | 35 | 40
TIRES USED AS SINGLES
1860 2030 2190
D
2190
E 1860 2030
TIRES USED AS DUALS
C 1260 1365 1475
C 1430 1565 1690
D 1430 1565 1690
C 1380 1515 1630
D 1380 1515 1630
Wheel Limit*
Size of Max.
Max.
Code
Wheel Load
Press.
(L b..)
(PSI)
2350
40 16.5 x 6.00
ZK
3170
40 16.5 x 6.75
ZJ
16x6Vz L 2780
40
ZF
16.5 x 8.25 2750
55
ZH
XW
15 x 6 JJ 1910
85
55 15 x 6 JJ 2040
XX
2780
55 ZT 19.5 x 6.00
2440
55 Zx 16 x 6 KS
55 16.5 x 6.00
ZW
80
40
Fig. 3E-6--Tire/Wheel Load and Inflation Pressure-C Models
Inflation Pressures (PSI)
| 45 | 50 | 55 | 60
2350 2500 2650
2780
2500
2350 2650 2780
1580
1815
1815 1930 2040 2140
1750
1750 1855
1970 2070
Max.
Press.
(PSI)
70
85
85
70
Location For:
70
• Maximum Load
70
• Maximum Pressure
95
• Wheel Code and "Radial'' Stamps
75
• Wheel Size Stamps
&5
wear is discussed further on.
M isalignm ent W e a r
This is wear due to excessive toe-in or toe-out. In either
case, tires will revolve with a side motion and scrape the
tread rubber off. If misalignment is severe, the rubber will
be scraped off of both tires; if slight, only one will be
affected. The scraping action against the face of the tire
causes a small feather edge of rubber to appear on one side
of the tread and this feather edge is certain indication of
misalignment. The remedy is readjusting toe-in, or
rechecking the entire front end alignment if necessary.
Uneven W ear
Uneven or spotty wear is due to such irregularities as
unequal caster or camber, bent front suspension parts, out-
of-balance wheels, brake drums out of round, brakes out of
adjustment or other mechanical conditions. The remedy in
each case consists of locating the mechanical defect and
correcting it.
Cornering W ear
When a truck makes an extremely fast turn, the weight
is shifted from an even loading on all wheels to an abnormal
load on the tires on the outside of the curve and a very light
load on the inside tires, due to centrifugal force. This
unequal loading may have two unfavorable results.
| 65 | 70 75
2920 3050 3170
LIG H T T R U C K S E R V IC E M AN UAL