metrompg.com series | Highlighted on Fuelcons
In this further post published on metrompg.com, the impact of tire pressure on rolling resistance was assessed using two different vehicles: a 1998 Pontiac Firefly (Geo Metro) and a 1999 Toyota Camry. The experiments were conducted on a paved slope with flat run-out. The methodology involved inflating the tires to different pressures (20 PSI [1.38 bar] to 60 PSI [4.14 bar]) and then letting the cars coast down the slope with engine off, transmission in neutral, and brakes released. Distances to marked “stop points” were measured using a distance measuring wheel (some kind of).
The Geo Metro had 155/80/R13 Goodyear Invicta tires. Distances traveled ranged from 479 feet (146 m) at 20 PSI to about 700 feet (214 m) from 50 PSI. The Toyota Camry had 205/60/16 BF Goodrich Traction T/A tires whereat achieved distances ranged from 569 feet (173 m) at 20 PSI to approx. 670-685 feet (200-210 m) from 30 PSI.
The experiments revealed variations in the results, even with the same tire pressure in the Toyota Camry, possibly due to factors like brakes not fully releasing or wind variations. Additionally, the data indicated that increasing tire pressure beyond a certain point did not significantly improve coasting distance for both vehicles. However, maintaining proper tire pressure appears to be crucial for reducing rolling resistance and improving fuel efficiency.
Source: metrompg.com