I pickup my car tomorrow...what does your experience show as to the best tire pressures for the Prius?
40 front, 42 rear. Some go with 42/44. One poster said 44/44. That may be pushing it a bity. Firmer tire semms to improve road feel, handling. Probably helps a tad on MPG, too. Haven't seen a post yet by someone who really knows their stuff abouty tires and suspension. Bob
I think you have it backwards Robert. The basic rule is to keep the Front two pounds more than the Rear. Toyota calls for 35 Front / 33 Rear - probably in the interest of Ride Comfort. Testing with the Classic proved to most people's satisfaction that going higher than that (to a point) yielded better handling, better mileage, and decreased tread wear, with a modest increase in ride noise/harshness, but not much. Most folks seem to be running 42/40, with some at 44/42. I'm sure someone somewhere is running even higher. Apparently the OEM tires on the classic were rated for higher pressures than on the 04. Being the curious type, I decided to run my own experiment, highly unscientific of course. When I picked up the car, I ran the first tank at 35/33. When I filled it up I upped the pressures to 40/38. It does corner better, and the mileage is improved (though since I'm still in breakin, that's far from conclusive). You do also hear the road ripples a little more with the higher pressure, but it's a quiet car to begin with, and with low engine and wind noise, it seems to me that road noise is a larger component of ambient noise than in other cars. It's not obtrusive, and doesn't interfere with conversation. I don't see any degradation in ride comfort. I'll probably go to 42/40 when I'm done with this tank. I'm sure others can give you precise numbers on how mileage is affected.
There have been some posts regarding the car 'wandering' at high speeds. I have found that this is related to tire pressures. I had mine at 40 all around. When I went to 42 rear and 40 front, the wandering stopped! I think RobertO has it right. Sure made a difference with my car.
Don't have my car yet, but a couple thoughts on using such higher pressures. 1.) The car's suspension is not optimized for it. Therefore, it may even be harsh on suspension components. 2.) Stiffer sidewall's can be detrimental to handling at the limited. For instance, less forewarning prior to tipping, or flexing suddenly (it is not a light car). 3.) Most tires handle skittishly in the wet when they are so much overinflated. However, in the snow, a harder tire (I am told) enhances its grip. Though this may be variable given the respective temperature and snow condition. 4.) It improves mileage...
I have 42 in front, 40 in rear, and get great mileage - a recent trip was 52.5mpg at speeds averaging around 79mph. A lot of downhill stretches though, in the 140 total miles!
We're nearing the end of the Winter season here in Wisconsin. If I bump up my tire pressure to 42 Front/40 Back, do I have to be concerned with fluctuation or anything in the tires when it warms up? Or, is 42/40 a pretty good tire pressure for year-round driving? Chris Hofer Fond du Lac, Wisconsin, Millennium Silver, #9
Rule of thumb - every 10 degrees Fahrenheit rise in ambient temperature yields a one pound increase in tire pressure. You can maintain the same pressure year round, but not without checking and adjusting.
I have experimented quite a bit with tire pressue on my '03 and the '04. I am settled in on 40/38 (front/rear) on my '03 and 42/40 (front/rear) on my '04. In both cases the ride is a bit stiffer but much more crisp and "accurate" if you will, with less "wander" at high speed. Also, at least on the '03 for sure, the mileage increased 1-2 mpg without a doubt. I have 19.000 miles on the '03 stock Potenzas and the wear is good. The pressure was a real issue on the wear on the stock Potenzas from what I hear, and everyone seems to agree that the wear on the Potenzas was worse at factory recommended pressures and better if you ran at higher pressures.
