Same ive got 18's on mine with 235/40/r18 firestone wide ovals on them and run em at about 3litthey have a little bit of sidewall flex but absolute even wear on all 4 tires

 

I wanna say it's totally depend on driving equation.If you wanna high speed driving, should use heavy tire as it can give you sustainable service.

 

I wanna just say it should be select based on your driving speed. As well as it should be keep concern to check Tyre on regular basis.

 

I Like mine closer to 40, I try and keep them around 37 because I have 19's with a 35 series tire. Personally with 17's and a 45 series tire I wouldn't go under 35.... But that's just me. just try and keep it between 33-42.

Its really preference! Let's try and hope it will be good choice.