[Rev]

Since both tires rotate at the same rate with a spool (locked differential), and since each tire must roll over a differnt length of pavement, then some slippage of tire to pavement has to happen.

It might be dragging of the outside tire on the curve, or it could be spinning of the inside tire of the curve (more likely), but one or the other tire has to slip on the pavement if you go around a corner with a spool (locked rear axle).

Hope this makes sense.

Rev