TannusArmour Tire Insert, No Flat Bike Tire Liner, Puncture Proof Bicycle Tube Protector, Stops Flats from Thorns and Goatheads Compatible with E-Bikes, Mountain Bikes, and More 20" x 3.0-4.0"

This insert has performed very well in the month I’ve had it. In the 6 months I’ve had my bike I’ve had at least 7 flats and most were from little pieces of metal from the street cleaners bristles and small glass shards. All would barely break through the tire but with the weight on the back tire they’d cause a flat. Always the back; insert angry face!!The second day it was in I pulled a staple that went straight into the tire out and the day after that a 3/4” finishing nail that went in at a slight angle. Neither punctured the tube and what I would’ve spent on replacement tubes has already covered a decent portion of the cost of this. I can still find glass shards and fine metal pieces but I’ve stopped even looking after seeing it take the nail and not go flat.I’ve seen reviews about this not having instructions and that’s wrong. They’re literally embossed on the side of the insert. It’s a few simple steps; deflate tube, clean insert, put insert into tire, tire on bike, re-inflate. But honestly if you need more that that you probably shouldn’t be working on your own bike imho. The only thing that wasn’t stated was that you may have to trim this if your size falls within a range like mine 3-4” insert for a 3” tire, but that’s kinda common sense and if you held the insert against your tire without trimming you’d see it’s way over sized. For this I put the whole insert into the tire, traced where it touched the edge of the tire and then cut 1/8” inside that line to give the tire bead space to seat in the rim. Like magic the amount I cut off was very close to 1”Lastly I’d like to point out something about sizing. The 20x3” tube I first put on which is my bikes size was too big. I felt this as I put it on. There’s just too much rubber when this insert takes up 1/3 of the space in the tire. I did my best to stretch it out and have it fit smoothly in the tire but there seemed to always be a spot it bunched. Plus I couldn’t really pump more than 20psi into the tire despite the bike calling for a min of 24. I should’ve trusted my instincts but recall reading another review saying someone was a clown for saying you need to size the tube down. Well last week I got a flat, was still able to ride to a safe place to change as the insert doesn’t put your rim on the road and the flat was caused by a small pinch in the tube. Not even against the rim just a tiny fold in the center of the tube where it sat in the insert. I got the next partial size tube smaller; 2.75-3.3” and it fits much better and took the correct psi.

My ebike has 20x4 tire and I've had three Flats on the rear. A bit of research later an I picked up some Tannus Armour and some Slimed. I installed it on my rear tire in under an hour, not too hard if you follow the instructions, and so far so good after 3 weeks.

I have used this product before and am happy and have not had a flat thus far. First Bike had for a year and never had a problem. Second Bike just installed tannis liner so hope I get same results.

I thought the product was a bit pricy for what you got. You have to push this lining into your tire and make sure the bits that stick out either side are even because when you put your inner tube in it will fold over the inner tube. Make sure you half fill your inner tube before inserting it. You won’t be able to put as much air in the inner tube as you usually would. There are NO instructions I clouded with this. Do not trim the li we at all it is meant to fold over the inner tube

the foam itself is very puncture resistant and it does exactly what its supposed to do.important note: someone told me you should use a smaller tube than normal to allow the foam to expand inside the tire. DO NOT DO THIS. whoever said that is a certified clown from the university of clowns. with a smaller tube the tire and tube are loose and will eventually fail despite being at the recommended psi. if you get this just use the same tire tube size.