For Tyson, or more specifically for his OCD, there is good dirt and there is bad dirt. Times when it’s allowed and when it’s intolerable. His OCD is more based on conforming to a structure than cleanness, but that doesn’t mean it won’t affect him.
Mud on the ground is fine. He can touch it without a worry. Mud on his boots is fine. His boots are there to walk in the mud so he doesn’t. That mud getting onto the carpet is not fine. It’s the exact opposite and something he must fix that immediately.
If Tyson is wearing his everyday clothes and gets coated in mud, Tyson has to go shower. Those clothes have to be washed. As soon as possible. Sooner. Now. It would become an incessant buzzing in the back of his head. He could delay caving to that need to finish whatever he was doing, but he would have to do it and Tyson would be left feeling rattled afterwards.
If Tyson was wearing the clothes he saves for taking his dogs on hikes and got completely covered in mud, not just over his clothes but also on his face and in his hair, Tyson would sigh, scrub off whatever he could feel on his face, then carry on with his day. No problems.
When wearing those clothes, he is supposed to get messy. It’s fine. The bit in his hair would irk once he realised, but it wouldn’t agitate his OCD in the same way. That was how Tyson got through P.E. at school, his P.E. kit was supposed to get muddy. It was okay. It would be okay. There was nothing to panic about. Nothing had gone wrong.
In this same vein, Tyson has specific clothes to wear when tinkering on his motorbike or other machines. He can get covered in grease and oil, even wiping it off his hands onto his shirt like a regular grease monkey without batting an eye. He’ll want a wash once he’s out of those clothes, but for the duration that Tyson is wearing them, he may as well be wearing armour.