What if I decided to go 35 tires would it be a problem with Dana 30

 

I ran 35" tires on a Dana 30 for several years. You will probably want some C gussets to support the axle C's with the extra weight of the tires, but 35's on a D30 will work. If you are planning on going to 35" tires just get them now. Same the step and money. If you get the 35" tires then you will probably want the 4.88 gears.

 

The tires you listed are basically 33s and even 4.88s are a steep gear set for that tire size with the Pentastar. Certainly not out of bounds, but pretty aggressive.

The shop you're dealing with might not have a full appreciation of what the Pentastar brings to the table. Their advise would be well suited for the 3.8L but not so much here.

Also, with a 2.5" lift you can get a lot more tire in there.

Take a look at the FAQ for more info and always better to get a few miles on new plus size tires so you have a real feel for the appropriate gear set.

 

I have a 12 jku auto on 37s running 4.88. The 2012 is a different animal. For 37s if I had it to do over I would go with4.56 because on the interstate the rpm's get a little high at 70 around 3000. And with the Dana 30 the pinion gear gets really small with 5.13. With that said I think 4.56 would be a good choice.

 

What about doing 35 as daily driver 30 mile round trip

 

What's your intended cruise speeds?

Also, I'm assuming pretty flat terrain to roll over.

 

Highway speeds and flat

 

People's idea of highway speeds range from 50-80mph. A huge difference if you're generally rolling at 50mph on rural 2 lane highways or 70mph on the interstate.

 

Your correct sorry but very open roads about 70 mph speed light though is 75

 

I don't think you'll have any problems.
no hills where you live.