Quote:
Originally Posted by qx4dude
I get the low PSI = soft ride / high PSI = harsh ride concept. But again, CAFE is what started the race to high MPG that all automakers are doing - so wouldn't it make sense for automakers to raise door sticker pressure another 5-10 PSI while tuning / compensating the suspension for a softer ride.
MPG is typically the #1 factor that new car buyers consider, so again, if running tires at max pressure is "safe", why do most manufactures have door stickers in the 32-36PSI range?
For some comic relief, here's a fun video on the effects of handling when the tire's contact patch is altered. They ran a Mercedes AMG with P125 / 60PSI tires around a track. Again, it's an extreme example, but it does illustrate the effect that changing the contact patch has on handling.
Sorry, couldn't find a video with bicycle tires...  |
Which is easier, designing a suspension to work better, possibly requiring more expensive parts, or simply keeping the tire pressure low for similar effects? While a lot of consumers are concerned about fuel economy, a bigger factor is price. It's cheaper for companies to keep pressures in the mid range to promote a better ride than it is to develop better suspensions and possibly have to increase the price of the vehicle.
I know your example was not meant to be taken seriously, but increasing the pressure inside the tire is not the same as configuring a vehicle with tires not up to the challenge of guiding the vehicle. Even at 60 PSI, there is still the small bulge where the tire meets the pavement on my tires. That would indicate to me the tire is still making good contact, and the tire is not acting like a bicycle tire that is higher in the center than the edges.
BTW, now that I think about it, guess how many PSI are in my bicycle tires? I keep them at a nice 125 PSI, as recommended. If my tiny bike tires, that are much thinner than car tires, and do not have the type of steel belt construction can handle 125 PSI, with no suspension, then my tires at 60 PSI have no risk of a blowout simply due to the pressure. Are the loads completely different? Yes, but again the load on my tires hasn't changed. If they could handle my 2400 pound car before at 30 PSI, 60 PSI isn't going to blowout the tire.