16" Wheels
Ok, right off I'll say I don't have any pictures of 16" rims for help.
So now the availability thing. If you don't mind running 225's or narrower, you have decent selection in 15 and 16" rims. Decent, not great. And actual performance tires are more limited than that. But, if you want anything wider than a 225, your options fall off a cliff. I went to Summit, which doesn't have everything but they have a decent selection. I searched by 15, 16, and 17" rims, just like roccodart440 did. But then I went a little further, and limited tire height to 24-28", because that's about all you can do with the stock tubs. I also only looked at radials, because if you want to run bias ply's you only have a couple choices anyway. Then I looked at the available tire sizes and ignored anything smaller than a 235 and larger than a 275, because a 275 is the best you'll do on a Dart with a 1/2" spring offset and stock tubs. Bigger than that requires much more significant modification. I called out 245's because that's a fairly safe bet for a wide tire on the back of a Dart that doesn't usually require cutting or moving anything with the proper backspace. I just took a screenshot of the relevant sizes, blocked out some of the front runners (you know, like a 26x6x15) and really wide drag radials (ie, 26x12x15) and added up the rest.
15's- 36 choices. Notice though that in each size you only have a few options. Like 245's? well, there's 6.
16's - 44 choices. That's a little misleading though, because 29 of them are in a 235/60/16, which is a 27" tire. If you don't like those, you only have 15 choices. 245's? Yeah there's 7.
17's - 378 choices. And a lot of choices in the useful sizes, like a 235/45/17 (70!) 245/45/17 (70!) or 255/40/17 (40!). Just in 245's of various heights there's 124 choices.
And that doesn't even address quality of tire, because a bunch of those 15 and 16" tires are hockey pucks, where in 17" there's a better selection of performance tires. So that's where the "no selection available" statement in the 15" and 16" rims comes from. If you want to run 215's or 225's you have some selection. But if you want anything wider than that, yeah, selection pretty much sucks compared to 17" or 18" rims. Oh, if you're curious, if you follow the same rules and look at 18" tires (24-28" tall, 235 up to 275) you get 773. And 262 of those are various heights of 245's.
Ok, right off I'll say I don't have any pictures of 16" rims for help.
So now the availability thing. If you don't mind running 225's or narrower, you have decent selection in 15 and 16" rims. Decent, not great. And actual performance tires are more limited than that. But, if you want anything wider than a 225, your options fall off a cliff. I went to Summit, which doesn't have everything but they have a decent selection. I searched by 15, 16, and 17" rims, just like roccodart440 did. But then I went a little further, and limited tire height to 24-28", because that's about all you can do with the stock tubs. I also only looked at radials, because if you want to run bias ply's you only have a couple choices anyway. Then I looked at the available tire sizes and ignored anything smaller than a 235 and larger than a 275, because a 275 is the best you'll do on a Dart with a 1/2" spring offset and stock tubs. Bigger than that requires much more significant modification. I called out 245's because that's a fairly safe bet for a wide tire on the back of a Dart that doesn't usually require cutting or moving anything with the proper backspace. I just took a screenshot of the relevant sizes, blocked out some of the front runners (you know, like a 26x6x15) and really wide drag radials (ie, 26x12x15) and added up the rest.
15's- 36 choices. Notice though that in each size you only have a few options. Like 245's? well, there's 6.
16's - 44 choices. That's a little misleading though, because 29 of them are in a 235/60/16, which is a 27" tire. If you don't like those, you only have 15 choices. 245's? Yeah there's 7.
17's - 378 choices. And a lot of choices in the useful sizes, like a 235/45/17 (70!) 245/45/17 (70!) or 255/40/17 (40!). Just in 245's of various heights there's 124 choices.
And that doesn't even address quality of tire, because a bunch of those 15 and 16" tires are hockey pucks, where in 17" there's a better selection of performance tires. So that's where the "no selection available" statement in the 15" and 16" rims comes from. If you want to run 215's or 225's you have some selection. But if you want anything wider than that, yeah, selection pretty much sucks compared to 17" or 18" rims. Oh, if you're curious, if you follow the same rules and look at 18" tires (24-28" tall, 235 up to 275) you get 773. And 262 of those are various heights of 245's.