I’ve had a lot of time to ponder this question since I was in the market for a new pocket knife. Recently, I saw an ad on TV that showed someone slicing through the rubber with their blade, and it got me thinking: “Can you really cut a tire with just a knife?”
I have a good friend who has been in the tire business for 30 years and I called him up to get his thoughts. He confirmed that with enough force, you could cut through rubber tires with just about any sharp object—including pocket knives.
He warned me not to try this at home, but said if I was going to test it out on my own car’s spare, then be sure to wrap some duct tape around the blade first so as not to damage the tire further than necessary. But please don’t do this on anyone else’s vehicle!
The only other suggestion he had is always carry two tools in your glove compartment when driving: an air pump (in case of flat) and a jack handle or lug wrench, and have a spare tyre in your car trunk.
How to slash a tyre with a pocket knife?
First, start with the blade side of the knife facing up so that when you push down onto something, the blade is pointing away from you.
Then, use as much force as possible to push down and drag it across the surface of your object like a saw. Push with such strength that when you pull up on the knife, there’s an indentation in whatever material your are cutting through.
If this sounds too extreme for you, but you’re still worried about flat tires (and don’t want to get one just so can try out slashes), then go buy some duct tape! It won’t work quite as well if needed to do any serious damage or puncture repairs on rims or body panels, but at least it’ll give car owners peace of mind until they reach their destination safely.”