
Staggered vs squared setup
My x5 came with staggered 21’s, I believe the size is 275/40/21 front and 315/35/21 rear. Would this setup mean I would have to change the transmission fluid more often? Would that include the front and rear differentials? Probably transfer case as well? Could I run the front size in the rear as well to just make all of them the same? Would I have to do anything in my idrive if I decided to run all the same tire size? Would it even be beneficial to do that? Sorry for all the questions and thank you for any help!