Many people choose to tow their 2nd vehicle "4-down" i.e. with just a tow bar. Some choose to load their vehicle into or onto a trailer and others choose a "dolly" where only one axle of the 2nd vehicle is on the road and the second axle is on the dolly as seen in this picture I shot in Wyoming.
Now this post is not about the advantages and disadvantages of these three methods of towing a 2nd vehicle along on your travels but specifically about ensuring the tires on the dolly are the correct size and have the proper inflation to help you minimize tire related problems.
I'm going to take a different approach than you might suspect. Many times I start off by suggesting you get the individual tire loads and then consult tables. This time we can do a simplier method.
1. Look at the size tire that is on the vehicle axle that is to be on the Dolly. In the above case it is a P235/75R15
2. Check the Tire Placard which is usually on the driver door jam. In the above case the inflation suggested by GM is 32 psi
3. Confirm the load rating at that inflation on the OE size tires. In this case 1940# @ 32 psi
4. Confirm the tires on the Dolly are rated equal to or higher than the tires on the axle on the towed vehicle.
In the above case the tires are LR-D and at 65psi are rated for 1984#.
Logic would suggest that since the vehicle manufacturer has staff engineers with the specific duty to properly set the inflation pressure on the vehicle it would be wise to follow their suggestion unless you have specific load information to allow you to set the tires on the dolly at a different pressure.
There is one problem. The owner of the above dolly insisted that the tires only needed 35 psi as the dolly bounced too much when inflated to 65.
Have to wonder if he will remember our discussion when he has tire problems in the future.