Maintaining correct tyre inflation pressure helps optimize tyre performance and fuel economy. Correct tyre inflation pressure allows drivers to experience tyre comfort, durability and performance designed to match the needs of their vehicles. Tyre deflection (the tread and sidewall flexing where the tread comes into contact with the road) will remain as originally designed and excessive sidewall flexing and tread squirm will be avoided. Heat buildup will be managed and rolling resistance will be appropriate. Proper tyre inflation pressure also stabilizes the tyre's structure, blending the tyre's responsiveness, traction and handling.
An overinflated tyre is stiff and unyielding and the size of its footprint in contact with the road is reduced. If a vehicle's tyres are overinflated by 6 psi, they could be damaged more easily when running over potholes or debris in the road. Higher inflated tyres cannot isolate road irregularities well, causing them to ride harsher. However, higher inflation pressures usually provide an improvement in steering response and cornering stability up to a point. This is why participants who use street tyres in autocrosses, track events and road races run higher than normal inflation pressures. The pressure must be checked with a quality air gauge as the inflation pressure cannot be accurately estimated through visual
An underinflated tyre can't maintain its shape and becomes flatter than intended while in contact with the road. If a vehicle’s tyres are underinflated by only 6 psi it could lead to tyre failure. Additionally, the tyre’s tread life could be reduced by as much as 25%. Lower inflation pressure will allow the tyre to deflect (bend) more as it rolls. This will build up internal heat, increase rolling resistance and cause a reduction in fuel economy of up to 5%. You would experience a significant loss of steering precision and cornering stability. While 6 psi doesn’t seem excessively low, remember, it usually represents about 20% of the tyre’s recommended pressure.