Designing a AC Snubber circuit for 2 hp using AC snubber
Don't switch the load directly! There is already a contactor in the circuit whose One Job is to switch the load.  Have your relay switch the contactor coil. 

Now you need a much smaller relay, and your snubbing problem is much smaller. 

The contactor coil will also be an inductive load and may need snubbing, but nothing like the motor!