Castelli made their name catering to professional cyclists. That's fine if you're a small rider under 150-lbs. For a normal size person Castelli does not make a size that will fit you. I am 5'10, 170-lbs with a 33 waist. I ordered a size XL and they were so small I could not raise them above my thighs. I exchanged them for a size XXL. I was actually able to get these on but were too tight to be able to ride in them. As Castelli does not make a size XXXL I was forced to return them for a refund. Too bad because they look like quality tights. However unless you are a small professional rider you will have to find a different brand of tights if yo want them to fit.
Unfortunately Castelli sizes their clothes to fit tiny professional riders. It is too bad because these are really nice, well made tights. I am not a big person at 5'10 and 170 lbs. Knowing Italian clothing tends to run small I ordered a size XL. They were so tight I could not get them over my hips. I exchanged them for a size XXL. I could get these on but were so tight I couldn't move in them. Castelli does not make a size XXXL so I was forced to return them for a refund and I purchased a pair of tried and true Pearl Izumi's. Too bad. I really wanted these to work but until Castelli starts making clothes that fit non-professional riders I will have to stay away from their brand.
You will need to be a very small rider for these to work for you. This is the first time I ever ordered a Castelli product and found their sizing runs extremely small. I am 5'10 and only 170 lbs and the size XXL was too tight to ride comfortably in. As a size XXXL is not available I had to return them for a refund. Too bad as they look like a nice pair of tights if you can get them to fit.