To upgrade a vehicle with Chonkers (otherwise known as the Off-Road Tires vehicle mod), you first have to find a set of them. Chonkers can be found at gas stations and at the Chonkers Speedway. Sometimes they’re readily available as ground loot, but usually, you’ll have to smash something up to get them to drop. Piles of tires should drop a Chonker pick-up, and vehicles often do too. The pick-up will look like a single tire, but it represents a full set.

A Chonkers vehicle mod will take up one space in your inventory and is actually used just like a grenade. To upgrade a vehicle with Chonkers, simply select the Chonkers in your inventory then throw it at a vehicle. The vehicle will magically sprout a set of huge new off-road tires and a raised axel. That vehicle will now handle much better and drive faster off-road.

If you throw the Chonkers and don’t hit a vehicle then a pile of tires will spawn wherever the “grenade” lands. If you do this by accident, you can retrieve the Chonkers pick-up by interacting with the pile of tires. There aren’t many instances where you might want to spawn a pile of tires on purpose, although in a pinch, they could be used as emergency cover.