These are all the maximum recommended sizes when lowering your C/K or S-10/Sonoma GMC/Chevy 4/6. You might be able to go with wider/taller tires (I did <g>).

1988-97 Chevy/GMC 1/2 ton 4"/6" drop


 
Front
Wheel Size
Tire Size
Backspacing
15x7
235/60R-15
4.5"
15x8
245/60R-15
4.5"
16x7
245/50R-16
4.5"
16x8
255/50R-16
4.5"
17x7
255/40ZR-17
4.5"
17x8
255/40ZR-17
5"

 
 
 
 
REAR
  
Wheel Size
Tire Size
Backspacing
15x8
275/60R-15
5"
15x10
275/60R-15
6"
16x8
275/50R-16
5"
16x10
275/60R-16
6" - 6.25"
17x8
275/40ZR-17
5"
17x9.5
275/40ZR-17
5"
17x10
315/35ZR-17
6" - 6.25" ***

*** Must roll fenders for clearence.
 
 
 

1982-97 Chevy/GMC S-10 4"/6" drop


FRONT
Wheel Size
Tire size
Backspacing
15x7
235/60R-15
3.75" - 4"
16x7
235/50R-16
3.75" - 4"
17x8
235/45ZR-17
3.75" - 4"

 
REAR
Wheel Size
Tire size
Backspacing
15x8 255/60R-15 4.25"
16x8 255/50R-16 4.25"
17x8 255/40ZR-17 4.25"