Important question on X4 tire swap..

[drod]

My X5 M-sport came with 20" performance RFTs. I immediately swapped them out for Conti ExtremeContact DWS performance all-season. (BTW, they are awesome on dry, rain & snow) highly recommend them..

anyway.. i'm losing the X5 but gaining an X4 m-sport w/20" 310 wheel upgrade which also comes with performance RFTs. In order to get full value for my X5 trade in I have to re-install the original RFTs and remove the Contis. I will, however, have the Contis available for the X4, assuming they fit properly.

Question: will the X4 w/20" factory wheel upgrade accept them without a problem?

Current X4 tire size is: front 245/40/20, rear 275/35/20

Conti tires from X5 size is: front 275/40/20, rear 315/35/20

I read somewhere that wheels can accommodate slightly narrower or wider tires. According to a tire calculator I googled, it should fit with no problems. (unless i'm reading it wrong..) can someone confirm this? I'd hate to have to purchase another set of Contis.

link to tire calculator is below.

245/40-R20 vs 275/40-R20 Tire Comparison - Tire Size Calculator

I appreciate any real feedback..