Wheel locks are important on the old back rims, especially if you use a lube to install your tires.
I ripped two valve stems before I decided to put mine back on.
When a stem goes so does the air, real quick
Regarding tire sizes, and a lot of guys desires to max out the size on their bikes.
A 1.85 x 19 front wheel, which was super popular on KZ's is best matched with a 100/90-19 tire. A 110 is a bit wide for that size wheel which causes the sidewall to pinch in and the contract patch to be more rounded than ideal.
On the rear a 2.15 x 18 was very popular and the max size tire for that width wheel is a 120/90-18. Some guys use a 130 but again, that causes the sidewall to pinch in.
In terms of "best tires" is concerned, this an opinion based subject.
Pirelli Sport Demon's are sticky, expensive, and wear fairly quickly.
Shinko 230 and 712's are perfectly serviceable tires and dirt cheap. They do tend to wear quickly though.
Avon Roadrider's are both sticky and have good longevity. The Sport Demon's might stick a little better, but they wear faster.
There are lots of other good tires on the market. On the other hand there are a few stinkers too (my opinion of course.) Dunlop 404's for example don't stick particularly well and they wear fast. Kenda Challengers are cheap and serviceable, but they turn evil in the wet. And Meltzer Lasertech's tend to crack, an unforgiveable failure on a tire that's so expensive.
I have Shinko 712 on my other build and they stick like glue. I lean and accelerate hard in corners and haven't felt a tiny bit of slip. I can see where the tires made ground contact and I'm very close to the limit. A very confident inspiring tire. Over 1500k on them and not a sign of wear...
Tire wear depends a lot on your type of riding. Heard of Sport demon wearing fast, but also heard other guys saying they lasted longer than Avon RR, again type of riding. Also read the Avon RR crack when store your bike in cold environment. I don't know where you leave, but something to think about. Don't know if they fixed fit or if it was a bad batch.
Continental Conti Go! and Bridgestone BT-45 are good tires as well.
I just noticed while attempting the true my newly laced D.I.D. rear rim from Z1E that there are no holes provided for rim locks. There is a quite prominent serration in the area of the rim where the tire bead will seat I'm assuming to take the place of the original style locks. Not planning on any low tire pressure, full throttle launches, so I don't think it will be any problem. I haven't decided what to do for tires, (1974 Z1A) definitely not a concours restoration, and if I do actually get it to run and ride it won't be very far or very fast.
Former M.E. at Kawasaki Motors Manufacturing, Lincoln, NE
1966 W1 (the Z1 of 1966-50H.P. and 100mph!)
1974 Z1A (disassembled)
1976 KZ900B LTD (SOLD!) it's in GOOD Hands!
1978 KZ1000 LTD
1976 KZ900B LTD pile O parts!