Thank you for all of your replies. Some were funny and most informative. BTW: I was able to puncture my Kevlar tire easily in the depth of a tread groove, just as I read DieselDan related. Whiteknight's info about police riders and liners was most-interesting. Based on your collective advice, I've retired my diaper pin and will ride my Slime liners until my Kenda's treads are bare--barring repeat flats of-course!