Small cuts in the tread are normal byproducts of riding. It the carcass under the
tread is not cut, you can just ignore it, or fill the cut with Goop if worried. Carcass
cuts under 4-5mm can be patched from the inside of the tire with a tube patch
or a piece of tyvek type plastic contact cemented to the inside of the tire. If the
cut bulges replace the tire. There are very few choices of 16" tires, the one on
the bike is a good one. 1.25" tires are not really all that fat and rolling resistance
has not been shown to be closely related, if at all to tire diameter. Tire and tread
construction and materials, not diameter are determining factors. Kevlar belts are
always a good idea, if available. www.gaerlan.com
and Google for Poweron cycling
are two sites that have a variety of bent tires. www.hostelshoppe.com
Tires in the 28-32mm range are more commonly used in bents, but there are a few in
the 25mm range from Continental and Schwalbe in the sub 24" diameter size range.
Primo's tires are always a good choice, seem to be well made, not over priced.
The Stelvios from Schwalbe are felt to be sexy for a tire, but longevity has been a problem
for some users, including myself.