how to tell if a wheel is soft

i want to get back into skateboarding and i always order from the internet. longboarding wheels tell you the durometer but when it comes to skateboarding wheels. it doesn't tell you. so how do i know that im ordering soft wheels? btw i use soft wheels because my skatepark don't have soft concrete we got some hard ass pavement like for the road type of pavement. so can anyone help?