What size tires are on a 1990 K 1500 Chevy pick up truck?

The tire size on a 1990 Chevy K1500 pickup truck varied depending on the options selected when the truck was new. There wasn't one single standard size. To know for sure, you'd need to check one of the following:

* The sticker on the driver's side doorjamb: This sticker often lists the recommended tire size.

* The sidewall of the tires currently on the truck: The size is printed directly on the tire sidewall (e.g., LT235/85R16).

* The owner's manual: If you have the original owner's manual, it should specify the tire size.

Without access to your specific truck's information, I can't tell you the exact tire size.