* P235/75R15: This was a very common size.
* LT235/75R15: This is a light truck tire, often found on more rugged or off-road-oriented Blazers.
* Other sizes: It's possible to find Blazers with slightly different sizes, depending on the owner's modifications.
To know for certain what size tires your specific 1989 Chevy Blazer should use, check the sticker on the driver's side doorjamb or consult your owner's manual. The sticker or manual will list the recommended tire size and inflation pressure for your vehicle.