I've had serious tinnitus since about age 50 and I'm 64 now. As a child I raced karts. We ran open stacks. The races were a couple hours long on big tracks. WFO most of the time with the engine right behind my helmet. After every race my ears rang for about a week. Later I became an Army helicopter pilot during my war. I flew a Loach and wore a ballistic helmet with no ear plugs to interrupt hearing my radios. The new helmets had built in ear protection but I used the old Ballistic job. I am told most of my hearing loss was due to that. I started losing the mid ranges in my late 20's.
I raced MX for several years too, but we had small mufflers. Still, a pack of any kind of racing motorcycles are a big noise. I didn't wear earplugs, so that probably didn't help.
About age 50 I started riding again and I noticed the ringing of the ears lasted after each ride, then became constant. I'm so used to constant ringing now, I probably couldn't sleep if it went away. It's become an old friend.
I think the riding contributed to my tinnitus. I wear earplugs but only for about ten years. And not always.