169.43 miles (272.66 kilometres)
Dorchester to Leeds is roughly 290 miles by road (M3, A34, M1).
If you take the M6 and the M5 it will take approximately 4 hours and 13 minutes and is around 250 miles. Hope this helps :)
163.71 miles (263.46 kilometres)
19.67 miles (31.65 kilometres)