You could sense and correct motorcycle tire pressure without a gauge, but with your Radmission and abound tires, pressure changes may not be noticeable until checked with a gauge. Regular checks are important for optimal performance.
Radpower doesn't seem to publish a PSI recommendation for the Radmission. Aventon really doesn't say. Online, their owner resources has 6 categories, any of which might have recommended pressure. The FAQ category has 11 sections, one of which is maintenance. That says you should make sure your tires are properly inflated before each ride, but it doesn't say what proper inflation is. The Maintenance Tips category has 11 sections, 1 of which is Tires and Wheels. One of its 8 sections is PSI Level. There, they take two paragraphs to recommend staying between 35 and 60, as printed on the sidewall. The latter is 70% higher than the former.
They don't know the weight of the load (including rider), they don't know the surface, and they don't know what aspects of performance matter most to the rider. If absorbing bumps is most important, you want the lowest pressure that doesn't cause difficult or treacherous handling or endanger tire and rim.
If reducing rolling resistance is most important, it used to be thought that you wanted inflate the tires as hard as they and you could stand, to reduce flexing. That was tested on smooth surfaces, but even fresh asphalt is pits between pebbles. You want the tire soft enough to absorb energy hitting a bump but firm enough to return energy as it pushes off the bump. Racing teams have to find the fastest pressure for a given surface.
On more than one Abound review video, a fairly heavy user rode with 100 pounds of bottled water on the back. At least two reported that with the load, the steering was unstable as if the steering column was flexing. Mine is rigid. I think they'd neglected to increase tire pressure for the added weight. For handling, low pressure could let the tread squirm relative to the rim, but high pressure could let a pebble bounce the tread off the pavement in a corner.
The steering geometry of a bike means that when it tips left, the contact patch of the front wheel moves left of the steering axis. This turns the handlebars left, steering left so that centrifugal force counteracts the lean. If a fat tire is underinflated, the contact patch would move farther left, forcing you to fight the pull. If your handlebars aren't right, you could oscillate. (At 30 PSI, the steering geometry on my Radrunner balanced so well with the tire that I couldn't tell by the feel of the bars if I was straight up or banked over. At 10 PSI, the pulling was dangerous.)
In my limited experience, a fat tire handles better on pavement if inflated to the round cross section of a regular bike front tire. On my Radrunner, that's 30 PSI, the maximum safe pressure for the tire. However, fat tires are often used for loose surfaces like snow, mud, sand, and gravel. In my experience, a tire with low loading (fat tire) and a round cross section will tend to slide sideways, up onto the loose surface if steering or cornering produces lateral force. My Radrunner was uncontrollable on snow until I reduced pressure to 10, which handled very poorly on pavement.
As with rolling resistance, the best pressure depends partly on the surface. I guess I should experiment.
