Since you have 17's, going to 18's would be a +1 upgrade, and going to 19's would be a +2 upgrade. There's a couple of important factors to consider when choosing between 18's and 19's. For starters, lets talk about the costs involved. Generally speaking, 19's will usually cost you more than 18's. If not for the rim, definitely so for the tires. Tire selection wise, both sizes offer plenty to choose from, so you shouldn't run into any issues there. Next, you may want to think about the weight of the wheels. Once again generally speaking, due to the fact 19's are a larger rim and will have more rubber surrounding, they usually weigh more than 18's. If you're just into the "show" aspect of a new set of wheels, then the following won't hold true for you, but it is something to consider. The heavier the wheel, the more of an impact it will make on the over-all performance of your vehicle. From acceleration to braking, the heavier the wheel, the greater of an impact it will have on those areas. The trick is to get the lightest wheel and tire combo you can in direct relation to the setup (weight) you have now with your 17's. That way nothing (or not much) will change with the performance specs of your vehicle. With 19's, you'll most likely run a lower aspect ration tire compared to what you would run on a 18. This isn't always the case, but for the most part true. A lower aspect ratio tire will give you the "corner ripping grip" you want from a tire, but at the cost of a little (to some a lot) ride quality. To plainly put it, the ride will get "harder". Here's a rule of thumb you can use, going to a +1 upgrade (18's in your case) will give you 10% stiffer ride, and going to +2 upgrade (19's in your case) will give you a 20% stiffer ride. Now once again, this isn't always true, but something you can refer to quickly if you're put on the spot and need to make a decision. Last but not least, and you touched base on it, the larger the wheel you put, the more it will "lift" your vehicle. Giving it what's known as the "SUV-tuner" look. The rims look great, but the space between the fenders and the tires just looks aweful. With a +1 upgrade, the difference is there, but not as noticeable. With a +2 upgrade, the difference becomes much more evident.... Just some things to think about before you buy...