[RileyRL]

I'm about to buy a Polaris sportsman 450 or 570, and the dimensions are 83x48x48. Length should fit with the tail gate down and something blocking the rear window. And width will be very tight. The atv weighs around 700 pounds and tail gate is rated at 300 lbs will this be an issue?

Post pics of your atv and ridgeline, and model of atv.

 

[Dnick]

You'll certainly want to make sure you have a good cable on your tailgate; and the answer to your question might have a lot to do with how much dynamic (bouncing) load you'll be putting on the tailgate back there.
If you're at all concerned, it will be simple enough to spread the load back up onto the primary bed by putting a sturdy sheet or planks that run the full length to sit under both the front & rear tires of your atv.

But I'm betting you're wanting to confirm if you're OK w/o that. Sorry, but technically, you'll be in the danger zone. There may be others with actual experience that can tell you what they've seen.

One thing I'd say is don't put a lot of downward force on your tie downs there in the back!

 

[DrZew]

I was in northern New Hampshire there was a guy that had a big can am atv in the bed of his ridgeline. He came 300 miles it stuck way out and it did not bother him at all. He said "No Problem". I use a enclosed trailer, best investment.

 

[HIDridgeline]

Mine fit with out a problem. Yamaha grizzly 450.

 

[John32070]

Agree about a small trailer idea. Took my ATV on my 4x7 on 2000 mile round trip to Utah last Sept. Repacked wheel bearings before I left and had no issues the whole time despite the naysayers. So much quicker loading/unloading with a trailer too. I would definitely do the wood plank idea, and wouldn't hurt to have an extra set of eyes to watch how close you get to the back window.

 

[Outfitter]

I have hauled my Rancher and my Recon many times in the bed of my first Ridgeline without a problem. I was mostly concerned with the loading since you have the riders weight along with the ATV weight on the tailgate during loading. All went well and I had some rough roads going into and out of our deer camp.