What is the wheelbase difference between the John Deere 7R 310 and 8R 310 Tractor?

The John Deere 7R 310 has a wheelbase of 115.2 in. and the John Deere 8R 310 Tractor has a wheelbase of 120.1 in., a difference of 4.9 in. The John Deere 8R 310 Tractor has the higher wheelbase.