peterbuk wrote:I have 1 in mine at the moment, have had for probably bout 2 weeks, i noticed it about a week ago, its still at 30psi, does it defo need replacing?
Its not good to have screws/nails/glass/any other hard bits penatrated the casing - if you are lucky it will only be a short one - you will only find out if you remove it, consider its length and spit on the damaged area (to check for bubbles). If you are truely concerned and drive long distance and/or in a brisk fashion, I'd prepare to get it fixed at a convenient time, remove the screw/nail/etc - if it leaks change the wheel and take the leaking tyre to get sorted then refit it.
In my case, one very dark very wet night, I was about 200 meters from my house, went around a narrow tight walled bend then suddenly heard/felt a loud glunck once every wheel rotation - drove into the garage took the wheel off and discovered about 90% of an old broken Ford cast iron manifold clamp had pierced the front tyre. I did not need a second opinion - that tyre was scrap!!