Purchased a 2022 MDX a spec with 20 inch rims and p255/50 R20 tires. It was recommended I go down to 18 inch rims for the winter ( live in Canada) ;as it was harder to source and more expensive for 20 inch rims and tires and some prefer lower surface area.

Normally I just go to my mechanic who I use all the time, but a friend just started working as an executive for a tire distributor and said I could get rims and tires at cost : cheaper than Costco as they distribute to them. He doesn’t know anything about tires but he said his guys said this tire size would work on 18,inch rims.

255 60r 18xl I tried to do a calculator online but am lost.

Really appreciate advice!