Im stuck on what size to get.
 

Ok I am about to order the tires!!!
Im lost on which to get.

I have a 69 ss chevelle that is stripped and awaiting tires and rims to start back halfing the car.

I am going with COY's 20x14 that will be custom powder gunmetal center polished lip.
As for tires im looking at the Mickey Thompson sportsman S/R
But lost on two sizes
29X15.00R20LT this from what pics i can find looks alittle small (rubberband).
and 31x16.00R20LT Which looks the size i want.

But from the drawing mockup i did the 31 looks HUGE!! and the 29 looks perfect?

I am going Modern Prostreet the rear will no be lowered and will sit an inch about rim. anyone have any ideas on one or the other for my 69 chevelle?

I would inquire about the position of the valve stem on your Coy's wheels. I seem to remember someone saying they moved where they put them but on the set I have they put the valve stem directly in line with the brake caliper. This little detail makes me hate these wheels.

Edit...sorry, I know you asked about tires, but wanted to share this nugget of info as it may save you some heartache.

Ok i will check it out.
Im going disk in the rear. but big brakes are not a passion to me. so if i have to run an 11" or 12" that is fine. but ill check with them when i order them.

I'd go with the 29s

31's are huge...but why wouldn't you build your car such that you could run either those or the 29's? It's a quasi-prostreet build with huge diameter wheels, so the more sidewall you can fit the better from a 1/4-mile performance perspective. It's a back-half project, so you can fit whatever you want and set your ride height accordingly.

Can you post the layout drawings for reference?