69 Dart tire size
Will a 245 60 15 on 15x8 fit on the back, and will a 215 65 15 on 15x7 work on the front? It is on stock suspension and 8.25 rear and 11" discs up front.
The tires
should fit, but whether or not that wheel combination
actually fits
your car depends entirely on the backspace and the ride height. A few things-
A 215/65/15 is 26" tall. Which is pretty much the upper limit for tire height in the front if you want to avoid cutting bodywork, like the lower front corner of the fender. Whether or not that tire actually clears when the wheels are turned will depend on the backspace on your rims and the ride height of your car. I would recommend a 15x7 with at least 4.25" of backspace, and it will still be close. Especially if you're lower than the factory ride height.
In the back, a 245/60/15 will also fit on a 15x7" rim. The "measuring rim", the rim size that the manufacturer uses to measure all of the specs they list, is actually a 15x7 for that tire. Mounted on a 15x7" the section width of that tire is 9.8", and while you can mount it on a 15x8 the 15x7" is just fine. A 15x7 with 4.25" of backspace should work as well, especially with a BBP 8.25.
It's
VERY important to note that a BBP 8.25 rear axle is not the same width as an A-body 8 3/4 rear axle with BBP axles and brakes. The 8.25" rear end is about a 1/2" per side narrower, which means you can use less backspace than you would on an A-body 8 3/4 that's been converted to BBP. Or even a SBP 8 3/4 actually (not as much though). So while a 15x7 with 4.25" of backspace with a 245/60/15 would be pretty close to the quarters on most Dart's with a BBP 8 3/4, the same wheel on a Dart with a BBP 8.25 will actually be pretty close to the springs. Which is a problem that can be solved with a small spacer if need be (probably not needed on most cars), whereas being too close to the quarter can only be solved by cutting stuff or getting a rim with more backspace.