quote:If that is so, then why are there variations among the same car as to what tires come on the car from the factory? You could buy a civic in Florida that will come with bridgestones, and the civic in Cali will come with Michelin...that would mean different spec'd pressure from the factory? Pressure has to do with load ratings of the tires, the size of the tires and wheels, and what the car manufacturer believes to be the best compramise between a given tire size and the best load capabilty at a particular pressure (given the average load the car will see), as well as ride comfort at that pressure. Many auto manufacturers are now listing two different pressures for different loads; if you look under the fuel flap of any late model VW/Audi, you will see one listed for avg load, and one listed for a full load in the car. The pressures on the sidewall are listed as "MAX inflation pressure;" they never give you a particular pressure to use. Although, to get more load rating out of a tire, you up the pressure.
Tires make the choice in pressures, not the OEM unless you are replacing with exact OEM replacements. Once you deviate from that, go with what is printed on the sidewall. For most all tires, 32 is a 'safety' number and can be used on pretty much anything passengercar-wise. On LT tires, usually the pressures are higher. I personaly have had great luck with 5lbs under the tires Max printed inflation
quote:This just tells me that they're cheap tires (surprise, surprise), not suitable for spirited driving through twisties. Throwing more air in them is not going to fix them. Actually, I've had plenty of Michelin tires that were also soft as butter and not suitable for spirited driving in the least bit. That doesn't mean a tire with soft sidewalls is a bad tire. Some tires are geared for comfort (soft sidewalls). Others are geared for performance (hard sidewalls). So, I agree with CapriRacer, tire pressure depends on load rating, and not whether I choose Michelin over Watchamacallit. Sure, it's OK to play around with the PSI to some extent, depending on what your priorities are when it comes to driving. [ November 21, 2005, 05:59 PM: Message edited by: Quattro Pete ]
To emphasize this, go to your local Pep-boys, buy thier 4-for-$100 4-ply tires, fill them to 32 psi, go drive on a nice curvy road, tell me what you think.