There are tire swings, and then there are tire swings. You can have some good fun with a rope looped over a branch and tied around a tire, but with a little extra effort and less than $100 you can do much better. This one has been the most-used toy in our yard and held up well for four years of sun, sleet, snow, and screaming children.

Supplies

Supplies

25 feet of 1/2" Nylon twist rope - $39 (50ft roll)
Nylon is a good outdoor rope. It's readily available and cheap with high strength and UV/moisture resistance.
Three U-bolts, 1/4 in. x 1-1/8 in. x 2 in. - $12
Six 1/4-20 lock nuts - $2.50
One eye bolt, 12 in. long, 1/2 in. thread - $4
1/2 in. nut, washer, and lock washer - $4 for a 6-pack of all three
An old tire (free)

Total cost at Home Depot as of March 2022: $60, full shopping cart here

Tools

Drill
Extra long 1/2-in drill bit (long enough to drill through your tree branch - a 12-inch bit costs about $17)
Wrenches or pliers
Scissors or utility knife
Lighter or match

Step 1: The Big Picture

Here's a quick overview of where we're going:

Make three lengths of rope with loops on each side
Attach them to your tire using three u-bolts
Attach a long rope to an eye-bolt
Install the eye-bolt in a tree branch
Tie the ropes together to finish the swing

Now, to the details!

Step 2: Make Three Lengths of Rope With Loops on Each Side

The goal here is three lengths of rope that measure three feet from loop to loop. There are two ways to go about this:

The easy way: Cut about 5 feet of rope and tie loop knots at both ends. Adjust one of the knots until you measure 3 feet from end-to-end, then trim the excess and use a lighter to melt the rope end (this prevents fraying). An overhand loop knot is super easy and perfectly adequate, but a perfection loop or poacher's knot are almost as quick and look a little cleaner.

The slightly-harder way: Do the same thing, but splice loops in the rope rather than tying knots. This is what I did, and it's actually pretty easy with braided rope. I used this video (4.5 million views can't be wrong), but here is a nice written tutorial if you prefer something you can print and quick-reference.

Step 3: Attach Three Ropes to a Tire With Three U-bolts

Drill or poke two holes in the top of the tire
Loop U-bolt through a rope loop, then poke through the holes
Secure with plate, nuts, and lock nuts on the inside of the tire
Repeat to attach three ropes, evenly spaced around the tire

Step 4: Attach a Long Rope to an Eye Bolt

Loop one end of a rope to the eye bolt (knot or splice). The rope needs to be at least long enough to reach from the tree branch to the tire, with a few feet of extra for tying a nice knot. Just use the rest of your rope - you can cut it to length later.

Step 5: Install the Eye-bolt in a Tree Branch

Use the long drill bit to drill a hole through your chosen branch*
Put one washer on the eye bolt, then push it up through the hole
Install a washer - nut - lock washer - nut on the top side.
Leave some room for the branch to grow. Notice how much my branch has grown in four years... it's time to loosen the nuts a bit to delay the tree growing completely over the eye bolt.
Tighten the nuts to squeeze the lock washer tight - this will help prevent the nuts from slowly unscrewing themselves.
Pro-tip - slipping a piece of leather or some old jeans between the rope and the eye bolt keeps the swing from squeaking when it gets wet

*A note on drilling holes through branches. This was a point of contention on my first rope swing Instructable back in 2013. We had some lively debate and even had an arborist weigh in on the side of drilling holes. It does indeed seem that drilling a clean hole is much better for the tree than looping the rope over a branch, where it will quickly wear through the bark and "girdle" the branch (my first swing did this to a branch in less than a year). There are ways to help protect the branch from a rope loop (like a piece of carpet between the rope and the branch), so feel free to use one of those methods if you don't like the idea of drilling a hole.

Step 6: Tie the Ropes Together to Finish the Swing

Loop the dangling end of your long rope through each of the three ropes attached to the tire and tie a knot of your choice. I chose a hangman's knot, which looks cool and makes a nice grip for kids to hold, but there are lots of good choices.

You may have to re-tie the knot a couple times to get everything to tighten up at the right height. If not, you're more skilled than me... :)

Step 7: Enjoy for Years to Come!

This tire swing is still going strong after four years of fun. It's often covered with snow, roasting in 100-degree heat, or holding five bouncing kids at a time. There's a bald spot in our lawn that testifies to many, many hours of play time.

Thanks for reading! If you enjoyed this Instructable, I hope you'll consider reading one of my fantasy novels, checking out my blog (DIY and engineering analysis of fantasy fiction), and connect with me on Facebook or Twitter.