What is the wheelbase difference between the John Deere 8R 280 Tractor and 7R 290?

The John Deere 8R 280 Tractor has a wheelbase of 121.3 in. and the John Deere 7R 290 has a wheelbase of 115.2 in., a difference of 6.1 in. The John Deere 8R 280 Tractor has the higher wheelbase.