37-inch tires must be ordered from the factory.

The 2021 Ford F-150 Raptor was finally unveiled earlier this month, and with the launch promo videos showing the truck going airborne, there are countless hordes of fans who are exciting about its tuning potential and how to make the most of it off-road. We know that it’ll be offered from the factory with 37-inch tires as an option – the largest of any production truck sold in the US – but what if you get a standard model with its 35-inch tires? Can you just fit 37s to your Raptor and call it a day? According to Ford, the answer is a resounding no.

Before you get all up in arms about the corporate overlords trying to force you to spend more than you have to on a readily-available option, listen up. According to Ford’s program manager for the F-150 Raptor, the frame of models offered with 37-inch tires is uniquely modified. These models have an adjusted rear cross member and support bracket that have each been relocated in order to make space for the larger and wider 37-inch spare tire. But it’s not all about fitting a bigger spare under the bed. The unique frame also requires a modified chassis, and the suspension has been altered too.

Front View DrivingFord

Frontal AspectFord

Other changes include unique coil spring suspension and recalibrated Fox Shocks with larger-rod shafts and taller jounce bumpers to better prevent the larger tires from rubbing on fenders and wheel arch liners when your Raptor is maximizing its suspension travel over big bumps and jumps. As a result, models equipped from the factory with the smaller 35-inch tires have more wheel travel and slightly smaller approach and departure angles. If you buy used and aren’t sure if the truck had 37s from the factory, you can tell by spotting a special “37” graphic on the tailgate while the Fox Shocks will also have unique graphics. And if you just want to fit 37s to your 35-equipped Raptor, don’t. Ford will void your warranty.

Side View DrivingFord

Rear Angle ViewFord