New owner with question

[Ram2500chick]

I just bought a 2007 Dodge Ram 2500. It came with stock 17 rims with 265/70/r17 tires. I would like to put 18” rims and bulkier tires. What’s the biggest size tire I can go without a level/lift kit with no rubbing?

 

[Shoveltuski]

Probably 275’s if your going w/ an aggressive M/T type of tire. Or a bit larger if your going w/ a less aggressive A/T type tire.
Consider a 2-3” leveling kit up front if you want to go bigger, it would IMO give the necessary clearance needed for more aggressively lugged M/T style up to 33” (or 35” A/T) w/o rubbing (too much). Can still use the shocks/coils you already have & The kit is relatively inexpensive & an easy (or inexpensively labored if your paying a shop) to install

 

[Marley]

I agree with a simple leveling kit, doesn't take much with these trucks.

I think 35's look ideal under the 2500 but with some penalty.
1. The already terrible gas mileage suffers some, I get 12 mpg with 35" muds.
2. If you tow heavy you'll need to regear with 35's unless your ok with lugging and rising engine temps.

Otherwise you got yourself some eye candy.