Since Ripcord keeps showing up, lets have a look at one of the first really fast
tanks in history - the BT tanks, from Soviet Russia!
A successful model built in the hundreds, the Russians learned a lot experimenting with the quick, nimble and cheap BT series. They tried new gearboxes, tank rocket launchers, even remote control! It also pioneered the proud russian tradition of jumping obstacles by way of sheer speed and finding crews with cast-iron balls.
Roadwheels were experimented with, making it one of the very few armoured car / tank convertible vehicles to see mass production.
(remote control version below, I think it's the one on the left - and yeah, it's completely blind. But when you wanna know if zee Germans had a field gun lying in wait... put that one out front
The BT was a nifty tank and a great learning experience for Russia,
and as followers of the thread may remember, it lead to the A20 prototype,
...which was the precursor to their most successful tank of the war.