Given how uncomfortable Tyson is in vehicles of any kind and how unsafe he feels, it’s odd that he feels more comfortable on his motorbike than in a car.
As with most things in Tyson’s life, it’s about having control. He doesn’t like having the control over his movement taken away from him any more than necessary.
He feels more fragile like that, very squishy on the road compared to the tin can death traps he hates so much, but Tyson has more direct control when riding his motorbike than he does when driving a car. His movements and the way he leans affects what is happening, rather than standing in the exact same position in the car.
Another factor is that Tyson doesn’t have as many bad memories related to motorbikes as he does with cars. He wasn’t stacked like sardines with other soldiers in the back of motorbikes, but in jeeps. He wasn’t having to navigate a landmine covered road whilst on a motorbike. He wasn’t watching another motorbike explode further down the road.
Tyson has two impulses related to his OCD around vehicles, only the first one applies to his motorbike as well. When stepping off or out of a vehicle Tyson will always put his left leg out first, despite being right dominant for both hands and feet.
When getting into a car he’ll buckle his seatbelt, unbuckle it, then buckle it again. When very nervous, he’ll continue that cycle several times over. Tyson isn’t aware of that tick’s origin point, only that he feels safer knowing the belt wouldn’t stick. His memories of a jammed harness locking him in place whilst under fire in the army are too hazy for him to remember now.