I've used Mr. Tuffy tire liner products on both a road bike and mountain bike for over 25 years and have generally been satisfied with the product's quality and usefulness. However, it's still possible for a Mr. Tuffy tire liner to inadvertently puncture a tube.
This manufacturer's tire liner will generally block small, sharp items like a piece of broken glass from puncturing a tube, but the liner won't stop a larger, sharp piece of broken glass or any type of nail, for example. Also, given that the liner is supposed to be seated in the middle of the tire, don't expect protection for the tire's sidewall.
The manufacturer's claim that their tire liner will Absolutely, Positively not cause tube damage isn't true.
When installed, the tire liner must be seated directly over the tube and generally centered in place all the way around the inside of the tire wall. This process remains difficult to achieve perfectly so that the tire liner is seated correctly. Frankly, it's nearly impossible to get both the tube and tire liner properly seated together, especially when re-mounting a Michelin Pro 4 Endurance tire model. There's a much slicker, slippery finish to the 2019 Mr. Tuffy tire liner product I received that makes it difficult to keep it in place while attempting to also position a tube. So, the tire liner moves around a bit, can end up not being centered over the tube, and is instead pushed off to either side of the tire, and therefore may end up with a small bend or crimp in the edge of the tire liner.
If there's a small bend or crimp in the edge of the tire liner, the end of the bend or crimp forms a small, V-like point that slowly rubs a hole in the tube and causes a flat. Mr. Tuffy tire liners previously had hard edges that historically caused flats. A significant improvement was the subsequent softening of the tire liner's edges so that flats wouldn't occur. However, a bend or crimp in a tire liner not perfectly seated can cause a slow leak and eventual punctured tube.
I bought a set of Mr. Tuffy tire liners in May, installed them in June, and new tubes in both my front and rear tires were punctured by a small, V-like point at the end of the bend or crimp in the tire liner. Today, July 16, the Mr. Tuffy tire liner rubbed another hole into a new tube because the liner slid out of its centered position and its edge became a point that punctured the tube. I've never had this happen before, and at this frequency, with a Mr. Tuffy tire liner product. I'm not happy that it cost me approximately $24.00 for three new tubes.
Nevertheless, I ride through a lot road debris on Pacific Coast Highway in southern California, and still believe this is a worthwhile product when its installation is achieved perfectly suc
Thank you for your feedback.