I print on half-page mailing labels, I've done tapes down to around a 20mm flywheel and had no issues with operation. Here's a set of graduated tach tape images and a nice page about making custom tach tapes by the Hikel boys. I thought I posted these in one of the documentation threads, but I couldn't find them.
If you have a compatible gear ratio, just measure the circumference of the flywheel and match it up to one of the custom tapes to get 24 stripes. You can also print the labels on plain paper and do "trial fits" of the flywheel if that works for you.
