Z-speed rated tires. â¦tires were all Z-speed rated. They were tested at some speed above 149 mph. In order to be more precise, tire manufacturers started testing at 168 mph (W-speed rating) and 186 mph (Y-speed rating). In the above picture you'll see 91W to the right of the size. The W of the 91W means the above Yokohamaâ¦.
I get this question many times and it is my opinion that the old felt should be removed and not covered over. I donât know why some roofers say âleave it onâ. I seem to me if you are going to the trouble of removing the shingles, you now have a chance to do repair on the roof deck by removing all the old felt.
Some say to put down a 15# or 30# layer of felt over the sheathing, then the metal panels; in other words, not to use purlins or the metal will condensate like crazy; enough so that the water will find it's way through the layer of felt.hen putting metal over a sheathed roof, what I've seen done is to run vertical furring strips on top of the sheathing, on top of the trusses, then put purlins cross-ways.