how to make groove on tire???

I am making tire in solidworks...i want to make groove on the surface of tire which is not flat...when i use extrude cut feature groove of different depth is form..

2 Answers

you can create a plane tangent to tire tread surface then make a groove by extruded cut, and then you use the circular pattern option to complete the operation

1-use extruded boss\base up to next
2-Revolved cut wit out border of tire

note
attached file is in SW 2014