15 lb turkey. Smoker goes up to 275. About how long to cook?

130 degrees for 22 hours. Best I've ever had.

That's fine but I would get her done, put a remote temp gauge in it and take off at 165,170 in the thighs. Keep warm then slice when ever.

Up to 275? Is that a electric smoker?
I start my turkey @ 275 for the 1st 2hrs - then raise temp over the next 3hrs to 350 for crispy skin. I smoke 12 - 13lb turkeys so a 15lb turkey might take 6 hours using this method.

Good luck -

Since I have a bigger turkey than expected I am going to 350 on the grill

Until it hits 160 degrees.

But you can always put it in the oven after smoking for a while to get the temp up. Doesn't absorb more smoke after a hour or so.

Just have to be patient. Most don't have the fortitude for 22 hour cooks much less 70 hour ones.

A must

Kind of like those ribeyes that sit in 110 degree bath water for 96 hours?