I put Coker Silvertown P205/75 R14 radials on my 57 & can't find recommended tire air pressure value. Coker is no help. They have a chat line but are not manning it & the email I got said to look on the side of the tire. That of course, is the maximum pressure. I doubt the 22# value recommended in the shop manual for bias tires is correct for a radial. Where can i get good info so I don't over or under inflate these tires?