Scott are the 245/60-15s for the front? On the back I wouldn’t worry at all, with your new engine there demise probably will be from something other than time or milage.
On the front it would have been nice to have some made the same date. I would just put them on though. I would at least wait till the white lettering turns brown to return them.
I had a tire thread on another site a while back on tires that last, time not to mileage. I think I will do Coopers from now on instead of bf goodrich’s. We have some old tires that look like new yet, and some newer tires that the time machine wasn’t kind. One set of Goodyear’s from early 90s that didn’t far well. A coupe guys replaced the tires every 8 to 10 years. I have some tires going back into the 90s, 80s and 70s.
Of the tires I looked at there was a set of M&H racemasters that I have that still look new. The old Armstrong’s in one of photo’s in that thread are still holding air. Lol
I have not had good luck with Goodyear’s sidewalls for some reason. Paul K going 140 on some aged tires makes me feel a tiny bit better about the 15 mile 120 mph average speed I did on some studded snow tires once.
https://psp.pontiacstreetperformance...c.php?f=5&t=51