Tire pressure is air pressure. The amount of air pressure within the tire. More air pressure within the tire decreases rolling resistance thus making it easier to roll. Less air pressure increases rolling resistance thus making it more difficult to roll. Not enough space to explain the science behind it.
Tire pressure is the recommended pressure by the manufacturer to get the best compromise of performance and comfort. Remember about 10-15 years ago Ford Explorers got the reputation of rolling over, Ford engineers recommended a low tire pressure for comfort despite the performance engineers request for better handling. There are 2 different pressures, the one on the tire is simply the Maximum the tire can hold under use and is listed on the sidewall, THe car pressure as explained is what the car maker wants but cannot exceed the tire makers recommendation. As to your bicycle, the lower the pressure, the more rubber is touching the ground, the more drag, making it harder to pedal, if you have the Ultra skinny tires, if you stay 5 PSI under the Max listed you will be OK. My bike HAD 75 pounds max listed, the wider BMX are lower pressured.
What happens when the tyre pressures are low: Lower pressures increase the traction, but the compromise is potential damage to your rims or pinch flats caused by the tube getting “pinched” between tire and rim. Ultimately the tire could come off the rim if there’s not enough pressure to force the bead into the wheel. What happens if the tyre is over-inflated: The over-inflated tyre, on the other hand, causes poor handling and braking as the contact point of the tyre gets reduced with the road. Too much pressure can cause your tires to quickly overheat and may result in bursting of tubes. What should be the normal tyre pressures for motorcycles Some factors affecting the tyre pressures include the weight of the motorcycle, quality of tubes and tyres and climate of the area. Also, one important point to take a note of is; the tyre pressures should only be measured when the tyres are cold. Possibly when the bike has not been run for more than 10 km or the tyres are at rest for at least 10 minutes after long riding. Motorcycle tyre pressure for Solo Rider. Front: 30 PSI or 206 kPa Rear: 33 PSI or 227 kPa Motorcycle tyre pressure for Rider And Pillion. Front: 30 PSI or 206 kPa Rear: 38 PSI or 262 kPa Note: Above mentioned tyre pressures are general readings and it is advised to follow the recommended tyre pressures as mentioned in the motorcycle users manual or generally that information is mentioned on the chain cover or the swing arm of your motorcycle.