Antenna towers have a load square foot rating. For example a Rohn HDBX is rated at 18 square feet of wind load at 70mph... I would not use it in a 90mph wind zone plus that 18 square feet is derated to about 6 square feet going from 70 to 90mph. That is without ice!
Rohn 25 guyed tower 40' tall(allowed wind load decreases with height) is rated for 22 square feet of wind load at 90mph
Wind load is the flat surface area presented to the wind. We had a discussion many years ago about how to treat the rotor of a wind turbine and most say treat the area of the diameter as a flat surface for the purpose of calculating allowed wind load.
Other manufacturers/tower heights will all have the specs available on the websites. In many places(so glad I live rural where they don't require permits!) you cannot get a tower permit without the engineering drawings and a plan of what you are putting on top of the tower.
If you are looking at used towers inspect carefully, if it has been painted run away because they are trying to hide rust. If the tower uses tube for the legs inspect inside for rust and make sure there are no ice bulges in the legs if you live where it freezes. Do NOT use a super light duty TV antenna tower like a BX64 unless you know towers very well. The old Rohn BX series used towers have aluminum rivets for the X braces and those rivets like to pop out due to twisting of the tower under a heavy load.
This is my US Tower TMM433HD crank up tower rated for 35 square feet, I have 15 on it and it is scary in high winds... advantage of the crank up is I can lower it before bad weather arrives. But since I bought mine for $3,500 prices have really climbed, it is now $6,600!!!!
I currently have the tower lowered, it either stretched or broke a U bolt that holds the mast in place letting the antennas spin! Wind over time can and will break things!
