N50-15 tire questions

I just picked up a pair of older MT Indy Profile N50-15 tires.  They're in great shape, great tread, no cracking.  

I recently switched from 245/45-17's to 275/60-15's, and everything I've seen so far tells Me I made the right decision.  The 17's measured 25 inches tall, and My mileage was around 8 MPG.  The 15's are 28.5 inches tall, and while I haven't measured My mileage yet, I still have gas 3 days after I filled up! It also shaved 500 RPM off My engine speed on the highway @ 75 MPH.  Unless Your geared about 2.45:1, AND have overdrive, I wouldn't recommend shorter tires.  

N=50 is that short. It's a 50 series profile, short and wide.

Thanks.  Yeah, 345-50-15 equates to a 28.5 diameter tire.  These tires should be around a 325-50-15 to 345-50-15, depending on what you read.  So, that's 27.8 - 28.5 diameter.  The smallest that I read was 27.5  But, these tires are measuring 26 - 26.5.  Guess I'm looking for someone with real world experience with these tires that can shed some light.  Is the info on the world wide web wrong or a bad guess?  Is there that much room for error with this kind of info?  Am I measuring wrong?  Like I asked originally, is that measurement based on diameter AFTER it's been mounted and aired up on a wheel?  Or, like people, do tires shrink with age?  :)

7T9_Tbird wrote: I recently switched from 245/45-17's to 275/60-15's, and everything I've seen so far tells Me I made the right decision.  The 17's measured 25 inches tall, and My mileage was around 8 MPG.  The 15's are 28.5 inches tall, and while I haven't measured My mileage yet, I still have gas 3 days after I filled up! It also shaved 500 RPM off My engine speed on the highway @ 75 MPH.  Unless Your geared about 2.45:1, AND have overdrive, I wouldn't recommend shorter tires.

Thanks John.  Currently, I've got MT Sportsman S/R 28x12.00R15 on the rear.  According to the numbers, they're supposed to have a 12" section width.  BUT, it wasn't quite that much.  They're probably equivalent to a 275-60.  Sorry, no pictures.  I wanted something wider, trying to build something with that '70s "street machine" look, but need to make sure these tires will be tall enough.

Here's what I've got currently, and how they look on my wagon.

what I've seen in off-road tires is that the size on the sidewall of the tire isn't always right, sometimes not even close, more than 2" usually smaller than the tire says

Jeff, Here's an old pic of N-50's on the rear of my Ranch. with 10'' wide rimS. The front's are G-50 with an 8'' rims. Sorry the pic isn't the greatest I don't recall having a rubbing issue front or rear, but I had air shocks which, was the cool thing ''Back in The Day''.

californiajohnny wrote: i have protrac N-50 15's on my monza. they are big! IIRC they are 12" in the tread width they do grow a little in the tread center when aired up, N=325 keep in mind they may be bias tires!!!  i can measure them if you need jeff...

Hey John. Yep, they're definitely bias ply tires. That's the look I'm shooting for. If you can measure them, that would be great. How do they ride? And what size and type of tire do you run on the front? Thanks

jeff they ride crappy for the first mile or two until the flat spots go away the front tires are bfg 195/70/13 (one went bad with a busted belt and are no longer available in that size ) but like joe said about mixing bias with radials... not a good idea! but if you do...bias on the rear NOT the front!!!! unless you want to create you own "joe stories"

i think there are a couple out there in radials or used to be?
i think mickey thompson does make some in radials the ones with the flame style tread pattern?
sportsman s/r

NEVER mix bias ply and radial tires on the same car!

I have run bias stickies on the back and radials up front, never had much problem BUT I also didn't try to take curves like I was at watkins glenn either. Ran  spools in a few cars too without trouble.

jeff, my pro tracs measure 27.5 tall 12 in the tread