Is it possible that highly inflated tires (such as 40 PSI) will lead to damage to shocks/suspension due to hastened wear and tear of those components?
I've thought precisely that, not that it's stopped me from raising tire pressures modestly higher than placard. It stands to reason: if the tire has less give, it will transmit more road shock through to the suspension. And you can feel it. For me the answer is to keep tire pressure increases moderate.
I disagree that 40 psi is "highly" inflated given the spec is 35/33 psi. My experience is that following the spec results in prematurely worn tires from excessive shoulder wear. Obviously there is the potential for a slight mpg improvement with lower rolling resistance. If you prefer to replace the tires more often vs. accepting the potential for greater suspension wear, that is your business. Some Prius owners seem to think that the front struts and rear shocks are "lifetime" items. If you want a good ride, depending upon the condition of roads in your locale, you need to be prepared to replace those at 60K-90K miles IMO. If you see substantial fluid leakage on the suspension parts, that is proof they need to be replaced. However, the lack of such fluid leakage is not proof the parts are good especially if you live in an area with high ambient temps (like here in southern AZ.) The very thin oil deposits on the strut body will dry up after a few months in 110 degree heat.
Many here drive their Prius with a slight increase in tire pressure (40 psi front, 38 rear). If there were major issues, they wouldn't do it.
I'd rather inflate to the 40's then suffer the poor road handling characteristics of under inflated tires, and yes the components meant to wear out, wear out, the gas in the shocks has no idea my tires are inflated correctly or under inflated. And at 60-80 thousand with new (better than oem) shocks, onward.
No. 40PSI is not "highly inflated." If anybody who swings wrenches for a living has ever told you that, do not let them anywhere near your car.
I've been running 44/42 for many, many years now... along with carrying heavy loads from time to time... without ever observing any issues.
Not on modern steel belted radials. That problem came from the previous era's bias ply tires. If 40 psi will cause a center wear strip, we'd already have thousands of members of PriusChat and CleanMPG.com and other fuel efficiency forums already reporting it. Specific to the Prius, this level of pressure appears to be reducing the edge wear strips, suggestive of underinflation, that many members reported when running the placard pressure.
