Looks like half use front and half use rear. Some times depending if off road or hwy. Some ask why chains at all? You may not need in some states buy I see WA and OR have laws you cant get around. Example on one part below.
The following vehicles are exempt from the chain law; however, in very bad winter road conditions all vehicles may be required to use chains regardless of the type of vehicle or type of tire being used (this is known as a conditional road closure). A conditional road closure may occur on any of Oregon's highways and are frequent in the winter on Interstate 5 through the Siskiyou Pass south of Ashland:
Police vehicles, fire vehicles, ambulances, and Department of Transportation highway maintenance vehicles when performing their duties.
A four-wheel or all-wheel drive passenger vehicle if all of the following statements are true:
a) It has an unloaded weight of 6,500 pounds or less;
b) It is operated to provide power to both the front and rear wheels;
c) It is carrying chains;
d) It has mud and snow, all-weather radial, or traction tires on all of its wheels;
e) It is not towing another vehicle;
f) It is not being operated in a manner or under conditions that cause the vehicle to lose traction.
A dodge diesel is over 6,500 lbs. Now I already out of luck.
If I could only get 75 gal water to freeze in the bed of the truck. I got it made