New to rims an tires

Hey I have a 1989 CR250R I wanna put gold rims on but I'm not real familiar with all the specs when it comes to buying just the rims not the whole set up. I know the rear rim has to be 36 spoke not 32. But my problem is on the rims a see for 89 cr250r they say 17" an not 18" Rear rims an the front rim is a diffent size also than mine. Do I just have a bigger after market rim or was this just the size of the gold rims.