Just got New Michelin Energy anyone know tire pressure

Try 40 psi front and 38 psi rear. That should improve the ride a bit too. Remember to have the front 2 psi more than the rear since the engine weight is in the front. If the ride seems harsh, drop it to 38/36, or all the way down to the door plaque numbers. If you want a bit better MPG, boost it to 42/40. I think you could take it safely all the way up to 55/53, but that wouldn't be fun.

 

Go with the sticker on your door.

 

You could listen to random people here who have no credentials yet who don't hesitate to tell you what they think can be done "safely," or you can go by the highly trained, highly paid engineers at Toyota and use the factory specification for inflation as listed on your door sticker.

Different tires don't have different inflation specifications. The inflation specifications are designed for the car, not the tires.

 

Actually the inflation pressure is based on several factors, including:
1. Load rating. The load rating printed on the sidewall is at the pressure indicated. The manufacturer determines what load they want to carry and choose a pressure based on that (load capability of the tire changes with pressure). They modify this based on further factors, including some below.
2. How much the tire will heat up at a given pressure. This is tested for, as it is difficult to calculate.
3. Whether the tire could be deflected enough to break the rim seal in hard cornering. Higher pressures make this less likely. Watch Motorweek test cars in the slalom, and watch closely the tire deflection. It's quite scary!
4. Ride noise and comfort.
5. Fuel economy. A higher inflation pressure will usually give better mileage, at the expense of ride harshness.
6. Keeping the tread flat on the road. Higher pressures can lower the load on the outsides of the the tread (by increasing the load on the center), wearing the center faster. Lower pressures do the opposite.

If you have the same size tire, start out with the recommended pressure. If you can find the new tire load rating you can compare it to the old tire (at the manufacturers recommended pressure - a tire shop should have these charts). This can give you reasonable grounds to raise or lower the tire pressure based on load carrying capacity.

As you can see, it's much easier to just go by the door sticker, and watch the wear of the tread. If the center wears faster than the edges, lower the pressure a bit. If the edges wear faster, check the alignment, and if it's ok raise the tire pressure.

 

The car maker's recommendation is a compromise between fuel economy, handling, and ride comfort. One can use a different tire pressure, up to the maximum listed on the sidewall of the tire, and achieve a different compromise. I use 42/40 to get better fuel economy at the cost of a harsher ride and more finicky handling.

Modern radial tires have very little wear sensitivity to pressure. My tires are all wearing evenly across their treads.

 

I use the numbers on the door. Many people run at higher pressures. If you do that, keep the front 2 psi higher than the back, and keep the pressures lower than the max on the tires.

Tom

 

You could listen to some pompous @§§ who has no credentials or much Prius experience, yet who doesn't hesitate to tell you what he thinks you should do, or you can listen to the experience of people on PriusChat who have owned Prius for years and have tried various tire pressure combinations. Since you asked in this thread, I suspect you may want more advice and discussion than use the factory specification for inflation as listed on your door sticker.

Many people who have used the 35 psi front/33 psi rear recommended "by the highly trained, highly paid engineers at Toyota" and pompous posters have found excessive wear on the edges of their tires, indicating under-inflation. It is these same "highly trained, highly paid engineers at Toyota" that specified Goodyear Assurance Integrity tires in the first place.

Many people on PriusChat have experienced better ride and MPG by increasing their tire pressure to the suggestions I have made previously. All my suggestions are within the safe operating range of pressure specified by the tire manufacturer, whom might be expected to know the safety characteristics of their tires better than the manufacturer of the car.

If "the highly trained, highly paid engineers at Toyota", and the pompous poster who speaks for them, really had all the answers, you'd still have your Integrity tires mounted at 35/33, right?

 

40/38 works for me. Almost 30,000 miles, and very little wear, and it is evenly distributed. I bet that many anti-OEM Goodyear drivers never experimented with tire pressures, especially those who dumped the OEMs right away. I find the Prius handles decently, and gets 50+ mpgs at 40/38. I also do autocross (Subaru, not Prius), so handling is important to me, and the Prius does just fine. The BT brace helps too. I would like to try some other tires, but at the rate I'm going, it will be another 25-30K miles. Cheers.

 

<div class='quotetop'>QUOTE(Bill Merchant @ Mar 21 2007, 11:41 AM) [snapback]409681[/snapback]</div>

Almost complete agreement except that no self respecting engineer would recommend those tires it was probably a compromise, under duress, with the "Bean Counters" who would of Thunk?

Wildkow

 

One of the hypermilers who was in the Prius Marathon has the Energy tires on a Honda Accord, pumped up to 60PSI, has over 70,000 miles on the tires, just half the tread depth gone, even wear across the tires. Makes you think.

Wayne

 

<_< There's no real final answer to the OP's question. Within the bounds of the tire sidewall MAX and Toyota's 'recommendation,' it distills to the preference of each driver. On my 2004, I ran the Integreties at 40/38 psi and started my 2007 Touring at the same. I traded my 2004 at 22,000 miles on the clock - the Integreties still had very adequate tread - I believe they would have yielded 35,000 to 40,000 miles safely. I really did not like the 'feel and ride' of the 2007 at 40/38 psi so in several steps I have lowered to 35/33 on the '07 Toiuring {Toyota recommendation}... a little softer ride and seems to handle better. I have not noticed a loss of MPG yet, but will be watching. I keep a 12v mini-compressor and quality analog tire gauge in my Prius to maintain pressure. Those "pencil" tire gauges are notably inaccurate and the digitals aren't much better. My analog gauge came from Racer Parts Wholesale, has a large dial easy to read and adjust to ½# psi accuracy.

Insofar as the "Toyota Engineers," the choice of GoodYear Integreties was more likely part of Toyota's goal to produce a base MSRP less than $20,000 and was, at best, a compromise. My read is that the Accounts had more to do with tire specification than the Engineers.