You can use the chart below to choose a boot and we think the chart is representative of the US shoe conversion. If you’ve determined your size in past Alpinestars sport boots, you’d be safe in choosing the same size as this brand runs pretty consistent from one model to the next (sometimes street and waterproof boots are not consistent however). I’d consider the width of the men’s sizes to be normal to slightly wide (D or E). I’ve always found this style boot easy to fit because the foot has a nice wide toe which is comfortable. Calf size is somewhat adjustable with the closure Velcro.
Go here for sizing information provided by Alpinestars