What is the ideal tire pressure?

[ace8726872]

So far, I have not done anything with the tire pressure. I think I can get a bit more MPG if I inflate the tires higher than the Ford recommended setting of 35psi (I think). What pressure are you running your FFH? If you inflate beyond the 35psi, does the ride suffer?

[jeff_h]

This topic will open debate similar to the frequency of oil changes.

 

I made a post around here somewhere that I checked my air pressures a couple weeks after getting the car, they were something like 35/38/32/40 which seemed a bit strange so I don't know if checking air pressure is part of PDI and if it is whether it was completed. So if you haven't adjusted the pressure on your own yet, check the levels in yours first and see if there are differences.

 

Anyway - I think the door sticker says 35 recommended, and I think the tires say 44 maximum, I set and keep mine at 40 all around and feel no difference in the ride from the varying pressures noted above that were in the tires when I got the car. At that pressure I still tend to get wear earlier on the outside edges of the tires a little sooner than in the center, which is strange since I drive a long commute with very few turns and might indicate under-inflation, however I'm not going higher to try and even things out since I know they are not under-inflated.

 

 

Added - in my estimation based on running higher and lower PSI in both the Prius and also in the previous FFH, the difference may be about 2 MPG better with the tires pumped a bit higher, however that is only a ballpark estimate based on looking at tank fill-up MPG numbers. Of course there were other variables involved (weather, route, traffic, etc) beyond just changing the PSI to really give that figure with a high degree of confidence, it's merely my estimate from comparing MPG on tanks with lower and higher PSI. So do some sampling on your own if you like and write back with what you find, it would be interesting to see if your observations are similar.

Edited March 22, 2013 by jeff_h

[acdii]

18" Goodyears are at 44 right now. Helped some, but not much, they are 51 PSI tires. I run my 2010 at 40 PSI, the Camry and Pri were 40/42, but dont remember which was front.

[ace8726872]

This topic will open debate similar to the frequency of oil changes.

 

I made a post around here somewhere that I checked my air pressures a couple weeks after getting the car, they were something like 35/38/32/40 which seemed a bit strange so I don't know if checking air pressure is part of PDI and if it is whether it was completed. So if you haven't adjusted the pressure on your own yet, check the levels in yours first and see if there are differences.

 

Anyway - I think the door sticker says 35 recommended, and I think the tires say 44 maximum, I set and keep mine at 40 all around and feel no difference in the ride from the varying pressures noted above that were in the tires when I got the car. At that pressure I still tend to get wear earlier on the outside edges of the tires a little sooner than in the center, which is strange since I drive a long commute with very few turns and might indicate under-inflation, however I'm not going higher to try and even things out since I know they are not under-inflated.

 

 

Added - in my estimation based on running higher and lower PSI in both the Prius and also in the previous FFH, the difference may be about 2 MPG better with the tires pumped a bit higher, however that is only a ballpark estimate based on looking at tank fill-up MPG numbers. Of course there were other variables involved (weather, route, traffic, etc) beyond just changing the PSI to really give that figure with a high degree of confidence, it's merely my estimate from comparing MPG on tanks with lower and higher PSI. So do some sampling on your own if you like and write back with what you find, it would be interesting to see if your observations are similar.

 

Great info, thank you very much. I will definitely check this weekend. Great to hear that you didn't feel any difference in the ride quality. I will try 40psi and see. My morning commute has been pretty consistent so if there is a difference, I should be able to tell, I hope.

 

Thanks again. I will report back with the higher psi next week.

 

Thanks.

[GrySql]

18" Goodyears are at 44 right now. Helped some, but not much, they are 51 PSI tires. I run my 2010 at 40 PSI, the Camry and Pri were 40/42, but dont remember which was front.

Same here, when the car was delivered the 51 PSI Goodyears were random pressures. Tried 44 PSI, then 40 and am back at 44 now because I like the ride/handling better here in So Cal.

MPG's? I don't know, don't pay that close attention to know if it changed. BTW, a good dial gauge is useful, those pencil gauges are not too exact.

Edited March 22, 2013 by GrySql

[ace8726872]

Crap, just found out I will be going to Pasadena for training next week so I won't be able to compare the difference in MPG at higher psi. Will do it the following week.

[jeff_h]

Crap, just found out I will be going to Pasadena for training next week

 

Say hello to the Little Old Lady for us.

[GrySql]

Crap, just found out I will be going to Pasadena for training next week

You and I must be frequently crisscrossing each other paths.

I'll wave next time. :)

Edited March 22, 2013 by GrySql

[ace8726872]

You and I must be frequently crisscrossing each other paths.

I'll wave next time. :)

 

Yeah, it sounds like it. I commute on 118 freeway and live in the SFV area. I will flash my lights!

[GrySql]

Yeah, it sounds like it. I commute on 118 freeway and live in the SFV area. I will flash my lights!

Yep, out the 210 to the 118 and up and over Rocky Peak ever so often, like last Tuesday.

[ace8726872]

Yeah, you are driving right by my exit at Tampa. I love going down on the other side of Rocky Peak but not coming uphill.

[acdii]

Here is a neat trick to find the correct pressure for you car, regardless of the tires.

 

Set the air pressure at the recommended levels, then on each tire, do this one at a time, take a piece of chalk and draw a fat line across the tread, now this will only work on pavement, so if you have a gravel driveway, do this in a parking lot instead. Then roll the car at least twice over the chalk line, but not so much as to totally scrub the chalk off. Look at the line, when the tire is properly inflated the line will be worn evenly across. Too much in the middle and over inflated, too much on the ends, under. It will also show if you have an alignment issue if one side is scuffed more than the other.

 

By doing this at each wheel you will find out what pressures to use in each tire. It is best to do this with a load as when the car is normally driven, if just you, then just you, but if it is you and your partner, then both should be in the car.

 

Now to get the most for MPG while still maintaining a safety factor for traction, overinflate to the point where you dont completely wear off the center but show a noticeable wear factor.

 

Also rotate often as the differences in tire pressures can cause uneven wear, and by rotating often, you maximize the life of the tires.

[lmp180psu]

I thought i remember seeing the sticker on the inside jamb of the drivers door say 34 psi all around for the 18" Goodyear's. That is what i set them to when i took delivery ( dealer had them at 36 i think) and haven't changed it yet. I haven't checked the pressures since which i probably should. My mileage has been pretty good so i haven't thought to do it, but i have almost 5000 miles and am scheduled for a rotation in 1.5 weeks. I may increase the pressures a bit soon.

[ace8726872]

Say hello to the Little Old Lady for us.

 

Man, Little Old Lady nothing. Pasadena and 210 Freeway have some angry people!!! Not like the nice folks who travel on 118 Freeway.

[hybridbear]

Ours came from factory at 40 PSI in each tire. Dealer lowered to 34 PSI when changing my oil :angry22: but I put the PSI back to 40. Ride seems great at 40 PSI

[expresspotato]

Hmm weird. The door jamb here on my Canadian version says 35 PSI recommended pressure for the 17" Michelin low rolling resistance tires.

 

Correction: 35 PSI is what the door jamb said.

Edited April 14, 2013 by expresspotato

[milleron]

Hoping to resurrect an old thread here.

I was somewhat astonished to find that my tires, the 18" Goodyear Eagle LS's on the Hybrid Titanium, came from the factory at 44psi. They were all the same, within 0.5 psi, so I must believe that this overinflation was intentional. For now, I'm leaving them at that pressure. because, although only driving the car for one day, I've seen a 17-mi trip at 40.5 mpg and a 10.2-mi trip at 43.5 mpg while handling and ride seem exemplary.

 

Any thoughts from the cognoscenti?

[GrySql]

I have the same tire, rated for a maximum of 51 psi, mine came at 32 psi or lower.

I inflated them to 44 psi for a while, then 40 but after a month or so returned to 44psi.

That is where I like them and will remain that way, the car rides and handle well.

The tire pattern shows well when I run from wet to dry, not crowned.

[acdii]

44 seemed to be the magic number on mine too.

[neod192]

I just set mine to 44, it was at 37 before. I can definitely tell the difference, the ride's a little stiffer - and that's a good thing! The guys @ Discount Tire warned me that the tire will wear out in the middle faster ... should I be concerned?

[acdii]

Use the chalk test I posted elsewhere to find out. Chances are you will not have uneven wear.

[GrySql]

The guys @ Discount Tire warned me that the tire will wear out in the middle faster ... should I be concerned?

 

Don't use the middle so much, corner faster to even things out. :)