After installation I had problems with a flat rear tire. Thought it was the tires. Brought to the store, no leaks were found. I let them know I used this tire pressure cap. They installed it and dunked the tire in water and it showed a constant leak under the cover. They couldn't stop the leak no matter how tight the plug was. Even with the tool provided. There were no issues with the front wheel leak. After filling the rear tire to 40psi and driving 30 miles to work, it drops to about 33psi, which is not safe. Buy something else.