Team Dynamics Wheels and Offsets

[cantfind1]

Okay so this seems to be done to death but just need some opinions.

I am going to get some track wheels and tyres not concerned about swapping wheels front to back so sizes are as follows

Front 18x9j et30(extends by 20mm over OEM CSL Rims) or et35(extends by 15mm over OEM CSL rims) Not sure if the 20mm extension will foul the arch with 235 tyres?

Rear 18x9j et 15(extends by 6mm over OEM CSL Rims) running 265 tyres on the rear.

All team dynamics wheels pro race 1.2 not sure if I can get 1.3's in these sizes, not sure of the benefits of the 1.3's over the 1.2's, any ideas?

Any thoughts on this set up welcome!?

Have been using this website to calculate the offsets

http://www.1010tires.com/wheeloffsetcalculator.asp

Cheers