I had asked the same question regarding the stripe issue a while back and got the same answer. There is a video that shows a striped tyre being done in normal mode without issue. Can't post link, search marc mcgurren on you tube and watch part 4 of his unboxing videos. Also shows ( and is mentioned in instructions ) that diameter may need fine tuning due to the tyre expanding while spinning to get the static diameter required. Having looked online at the instructions it appears that in special mode you move the cutting bit manually to the edges of the tyre. I'm still not sure if this is permanently saved. In normal mode it will measure tyre width before starting the cut which if you are unsure can be done by pressing the tyre width button before pressing start. I believe it comes with the carbide bit. I ordered on 04/12/20, got an email on 08/12/20 asking if i was sure as post was delayed 5 - 12 days, said yes and it was dispatched on 09/12/20. Tracking showed it stuck at Hong Kong airport for 4 days, then Cologne for 4 days and now in UK hub. Monday will be day 12 since dispatch. As soon as i get it i have striped GT12 and LMP tyres and non striped LMP tyres that i will cut so i can hopefully answer the rest of your questions. Cheers, mike