2004 X5 4.4i tire size and rim question

[crazy_camaro]

Hi. I have a 2004 X5 4.4i that and I need to change tires. the car comes with 255/50/19 in front and 285/45/19 in the back. I was thinking about Atturo AZ800. My question is what is the widest I could go in the back with my stock rims? My guy at the shop told me I could put 305s in the back. is that possible? not sure what the stock rim size is (probably 10 inch). Can someone give me their input? I like the look for the wide tires in the back.
Also if anyone has the Atturo tires installed, please tell me about your experience with these tires.

Thanks in advance

[crazy_camaro]

Anybody?

[TriX5]

Theoretically 305/40/19 and 275/40/19. I don't know who makes those sizes or if they exist.

[dkl]

Agreed with TriX5 (I think you meant 305/40/19 and 275/45/19 combo). You have to be super careful with staggered sizes on an AWD. Too much difference in rolling diameter differences between front and rear and you will be looking for a new transfer case in no time.

[TriX5]

oops, yes 275/45, sorry.

[crazy_camaro]

I think 275 is too wide for the front. Is there any possible combination of doing 255 in front and 305 in the back while maintaining the same rolling diameter?

[sprocket1200]

try the 1010tires.com calculator. this will help with sizing

[TriX5]

The 4.8iS uses 275 on the front....