I'm not sure how exactly this happened. I could not see any debris on the road that could have caused this. I might have over-inflated the tire. The max is 109PSI and I think I had it at close to 120PSI. The tire size is 700x25C. What do you think? The cut on the tube is is less than half of the cut on the tire. The tire is a Michelin Pro 4

Anyway, my main question is can I patch this? Or is the cut too big and the tire is compromised? Thank you!

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120PSI? Not sure what size tire or how heavy you are, but that sounds insanely high to me. Looking at the picture, I would not use that tire.

The ties size is 700x25C. I'm 160 pounds. I just checked again. The tire rating is 73-109PSI. My other tire max rating is 120PSI. So, I brought both to around 120PSI.

My main question is whether the cut is too big to be patched.

A) That tire is toast.
B) Max pressure is almost never the answer. Unless you're riding this bike in a velodrome, you'll want to back off the pressure considerably.

For the benefit of other readers -

Into the bin.

chuck it.

Its cut across the fibers so you must have caught something. Yes, tire and tube is shot.

oh well, like fishermen say: "lose one, rig one". sounds like when it happened, you didn't go down. hope it wasn't a long walk

I think 120psi on a 700x25 is way too high for a 160 lb rider, unless the bike itself weighs 100 lbs. 85 - 90 psi is more like it for a 160 lb rider on a 25 lb bike.

In general, never use the advertised max pressure the tire is rated for to set your psi. Setting the psi is all about the rider+bike weight and the tire deformation while sitting on the bike. And deformation is your frictional friend by providing a larger contact patch, especially around hard and fast turns, though too much deformation can be your snake-bite nemesis. There's lots of charts out there to help you determine proper psi.

As for the tire, retire it (pun intended).

If you were out on the road trying to get home, you could boot that tire with just about anything and get home on it. But I wouldn't use that tire with so many cut threads in the casing for anything longer than it takes to acquire a new tire.

A boot is just something you put between the tube and the hole. It can be a folded up 1 dollar bill, though 100 dollar bills are more impressive when you tell your friends. Or it can be a piece of tuff fabric like sail cloth or a piece of a plastic bottle you found on the side of the road and cut to shape.

In all cases, I'd consider a boot a very temporary repair. Mostly just for the purpose of getting me home or somewhere to get additional help.

As someone who is relatively risk tolerant and has attempted this numerous times in the past, I have to say this tire is not worth patching (unless it's a roadside emergency situation).

This

Maximum pressure means the limit of what the tire will hold, not what it should be inflated to. Tire pressure may actually increase as you ride, especially if the roads are hot.
If your bike said "Max Weight 300 lbs" would you eat until you gained 140 lbs?

100 psi means there's 100 pounds of pressure on each square inch! Woah! Think of gluing a patch over that cut and having it hold with all that stress trying to pull the cut open, while you ride over bumps and potholes, too.
The fabric casing is all that keeps the tire from blowing up like a balloon, and a cut interferes with that.

Tyvek scraps
I wrap my spare tube with a piece of tyvek from an overnight envelope. (or an event ride jersey number). It should make a nice boot, bigger and stronger than a dollar bill. I've only had to use dollar bills in the past, the tyvek has been waiting for a cut tire, for a couple of years now.

But the main reason for the tyvek is that tubes often stay in saddle bags for a long time, and abrasion weakens them at the folded edge. I've seen two or three tubes go flat soon after replacing a flat tube, and the cut isn't sharp, it's kind of worn down looking.

Rule of thumb
Big cuts only happen on new tires. Why is that

That tire is done. Nothing can make it safe.

Murphy's Law?

As others have said, ditch that tire. BTW-I vary around 150-155 lbs, and have Michelin Pro 4 Service Course 700x25 (actually measure 28 on my rims), and I run them around 80-85 psi without any problems. Actually get a more comfortable ride and if anything, feels faster at the lower psi. Wouldn't advise running any tire at max pressure.

No kidding!
The first massive cut I got was in the sidewall of a nearly new Marathon Supreme, in the sidewall.
Only thing I had for a boot was a piece of old inner tube, which bulged out the side, nearly catching the brake pad, for the 22 miles home.

After that, I bought a pack of the Park TB-2 tire boots.
They are reinforced so they can't stretch/bulge, and have adhesive to keep them in place.

A few years later, I got another massive slice (in the sidewall again).
It was large enough to put my thumb through it, and I was positive no boot would hold.
But since it was a 6 mile walk home, I pulled out the Park boots and gave it my best shot.
Incredibly, the boot worked perfectly and got me home.

You mean that's wrong?

You might get a tire boot, or use a dollar bill in the future. Won't make the tire safe but might allow you to ride home.