How many PSI do you run in YOUR tires?
 

I've seen a few discussions about safe levels of overinflation and "hyperinflation."
(See:)
http://ecomodder.com/forum/showthrea...es-2522-5.html

http://ecomodder.com/forum/showthrea...es-2582-6.html

However, I have yet to see a thread about what ecomodders run in their tires. Please post how many PSI, what sort of tires, and how your inflation compares to the sidewall max.

In my Mazda, I run 48 PSI in the front tires (Michelin Harmony, rated at 44 PSI) and in the back, I run 42 PSI (some off-brand Hercules tires, with no rating listed).

I recently jumped to 48/42 from 45/38. Based on my last few tanks, I think it's likely that the extra few PSI helped my fuel economy.

Your temps have risen recently right?

Here in NZ my 36psi's and 44psi's have 60psi in them.

12,000km driven in 6 months and even wear front and back:)

1337 -

I put them at the sidewall max of 51 PSI. Typically the tires are ~7 miles warm from city travel when I do this.

CarloSW2

50 PSI in all tires with a sidewall max of 51. I leave that 1 PSI out because it is difficult to gauge with my pump pressure meter which is analog and I want stay within sidewall max, as MetroMPG's A-B-A testing has indicated marginal or no real benefit after 50 PSI is reached .

I would go higher if the sidewall max pressure were higher. (60 PSI would be limiting case... Don't want it to get blamed on the high pressure if I get into trouble with omnipresent potholes on Indian roads.)

I run 32 in all mine as the sidewall says 36PSI, since the suspension is rather soft it doesn't affect the ride too much.

My tires say 35 max, and I run them at 34. I'm going to try to get higher PSI rated tires once these wear down, as I'd like to run them much higher, but I'd rather not risk it.

My tires are marked 44 psi and I'm running them right around 50, read when cold in the morning. I had to get used to the firmer ride but now I don't notice it.

Katana, you might try running your tires at 35-36 psi unless they're not in good condition. I found a handling improvement right around 40 psi when I gradually increased from 35.

For years and years, I ran my 32 psi and 35 psi tires at the labeled 32 and 35 pressures. Every time the tread wore down, it was worn on the outside with deeper tread in the middle. That is, even at so-called max pressure, they were still wearing more on the outside.

I now have two cars with 44 psi tires, running at 50. The older set has over 10K miles and the tread is still DEEPER in the center than at the edges, in spite of the high pressure.

Yeah, I also have 10k miles on my set and the observation is the same as above. Maybe it is the mechanism built-in in the tires by the mfrs to trigger a fresh tire purchase! ;)

And each time I service my car, stupid service engineers at the dealership keep making faces and repeat how over-inflation will wear out the center more than sides!

I'm a little confused by the question:

• absolute pressure - I'm running Sumitomo T4s with 51 psi front and 49 psi rear.
• relative pressure - My Sumitomo T4s are rated at maximum sidewall pressure of 51 psi so my relative pressure is 0 psi front and -2 psi rear.
• OEM pressure - Toyota recommends 32 psi for OEM tires that came with my 2003 Prius so my replacement Sumitomo T4s are running +19 psi front and +17 psi rear.

Let me suggest that one or more polls might be a more efficient way to collect the tire pressure spread. Of all metrics, I would be more interested in the 'relative pressure' compared to the maximum sidewall pressure value. But given non-USA folks use standard units, a relative percentage might be more useful and easier to deal with.

It is a good question.

Bob Wilson

44psi in the tires, 44psi sidewall max.

I'm running 50 psi on all four corners of the xD, brand new tires too ...

I didn't realize the sidewall stated max psi as 51. (Use to seeing 44psi)

Also dam dealer had the tires filled to 28psi, no wonder they try and scam you into tires for life with them ...

During snow season (December to end of March), I used the max on the sidewalls - 80 psi

During the rest of the year, I air 'em up to 100 psi. This does not 'crown' E-rated tires.

BTW, I get more than 100,000 miles out of a set of tires doing this.

Yup, 80psi here on the truck too.....too bad they don't make e-rated tires for small cars, then y'all could see how rough the ride is at that tire pressure :D

35 psi in winter, but now 40 psi with max sidewall of 44. Kumo Solus KH15.

I keep my wife's tires at max sidewall (44 psi summer/35 winter). I run 60 psi year round on my 35 psi max sidewall winters and 44 psi all seasons.

I've got 35psi rated all-seasons, Don't remember what brand. The book says to set them at 33psi so I pushed then up to 40psi. I see a big change in how far it will coast just going from the 35 to 40psi. But you can definitely tell the difference in ride with the stiff suspension the Jeeps have.

tasdrouille-

Have you ever had a problem running at 60 PSI? I'm considering running 55 or 60 in my tires. I bet the ride in the city would be hell, but 95% of my driving is highway, so I wouldn't mind.

You brought up an interesting point:
Some drivers want to compare tire pressure to the manufacturer's recommendation.
Others want to compare to the tire's sidewall max.

That depends on whether they (or you) think that one or either of those is an authority you want to place your trust in.

Further, the tire sidewall imprint is often much higher than the mfg. recommend. If the car came with 35 or 44 psi tires, you can buy 51 or 60 psi tires - then what's your preferred pressure? Mfg's recommendation will of course stay the same; they're saying that's what's best for the vehicle.

I'm not saying that I'd follow either. I'm running 50 psi in 44 psi tires and not scared. YMMV, as usual.

Big Dave-

What model of tires do you run? Our '99 F-350 Diesel (basically just for snow plow duty) has some Michelins, which spec for like 70-80 psi, I think.

If you search around darin did a coastdown test and found that the improvements aren't that much when you get above 50 psi.

I run 50 all around.

interesting..
The most I ever ran was 55psi in my last car. In my current car I try 40psi, sometimes I forget about it, my rear is probably around 15psi..lol

Compaq888 What do you drive?

Firestones running at 50 psi with a sidewall max of 44psi. The uneven wear from when i got the car is still there. They were "underinflated" at 32 psi and wore more at the shoulder than the centre.

ollie

Frank-

The outdoor temps during my most recent trip (a little less than 1200 mi last weekend) were actually lower than my last long trip. Last weekend, I saw outside temps of 35-55 degrees, and I managed close to 40mpg (see my fuel log). The trip before that was considerably warmer, but I had lower tire pressure and was a few MPG lower.

As a tire engineer, I find it very funny that if a reference pressure is mentioned, it is what is on the sidewall and not once is the placard pressure mentioned! This shows a bit of misunderstanding of the physics involved.

Never had a problem wear wise. Performance wise, I can't tell, but they always did the job I wanted them to perform.

Ride is hell at high pressures, but my ultramicrocar is a hardriding buzz box anyway and I enjoy getting over 70mpgUS and very long EOC glides... :)

Which is kinda FE heaven

Hi,
I've read SAE Paper 800087 and it is a good source. I'm new here but was wondering if any of the members have used the coast-down test protocol to measure pressure effects on Crr?

Nothing like a little observation for cementing a good model.

Bob Wilson

I usually keep mine at 30-35. They are rated at 44. I would go higher if Michigan had good roads. It handles much better at 40 but every pothole and every expansion joint every 100 ft is hell. I already have to replace balljoints once a year.

I'm running Sumitomo T4 (sidewall rating 51psi) at 60psi. I'll fill them to 60psi, then let them drift down to 50psi before topping them off again. 65k miles on them so far with no unusual tire wear patterns.

basjoos, how long does the drift-down take? (my guess is anything upto 3 months...) What is the mechanism? Valve-stem leak?

I have the Sumitomos as well and have been wondering if they were ok to push at or above sidewall (running them ~45 now). I'll have to bring them up to 50 and see how they do. (just a pain to fill them with my craptastic pump)

Sans screws or other debris in the tire, mine have held fairly steady pressure for the last month. They went down 10 pounds from end of September to beginning of December as a comparison.

wow some of u guys run alot.

i run 40 in the white truck and 30 in the grey and 33-35 in the camry..

I run 48 psi on my 51 psi max tires. They are at the end of their life and I have inspection coming up in April so I'm sure I'll have to pick up 4 new tires. Will be looking into LRR if I have to get the new ones. I drive a 4runner so I have to have a somewhat larger tire on the SUV.

I got the tires in the summer before last and it initially it took about about 4 months for the pressure to drift down as the oxygen constituent of the compressed air in the tire reacted with the rubber interior and the temps dropped as we went from summer into winter. Then as we went from winter to summer, the pressure pretty much held constant as the temps rose and I had to do another add in late summer. I last topped them off in Jan and haven't had to make any more adds since (other than the one that developed a leak from a nail and had to be patched. The tires are now 1-3/4 years old.

psi
 

I run recommended inflation pressures in the truck for regular driving (32/35 psi).For open-road high-speed interstate travel,I bump them up 3-psi,as per Toyota's recommendation.--------------- For the CRX,I run 44-psi,which is the max inflation pressure for those tires.Rides a little rougher but no issue for me.

A 1999 honda civic dx, stick of course:thumbup:

I'm thinking of putting the Sumitomos on the rear 2 wheels of my Mazda. How much tread do you have left? Do you have an estimate on how long the tires will go?

Wow, I must be the highest percentage above sidewall max here. Cooper Lifeliner GLS Tires - 35 PSI sidewall max - Currently running at 55 PSI.
That is 157% over the rating for the tire, no blowouts or unusual tire wear yet, and I've had them on the Lemon for a year and a quarter. I have hit potholes that could swallow a car, and traveled 100+ miles at a time, still no issues. Maybe I'm just lucky :thumbup:.