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As per my first sentence in #56, I understand the reasons for F/R tire pressure differentials. .....
My question again is: Is it OK to run different tire pressures, F/R, on vehicles where the same pressure is listed for front and rear on the vehicle placard?
Sure. The basic rules are:
1) Do not exceed the maximum pressure rating for your particular tires. Some have a max of 35 psi, some 44 psi, and some 51 psi. The numbers for your tire should be on the sidewall.
2) Do not drop below 26-28 psi for any tires on any car. Even those pressures are likely to result in reduced fuel economy and increased tread wear.
and 3) don't go crazy on the differences between front and rear. You can tweak the tire pressures until you are comfortable with the handling and comfort.
I don't really pay attention to the numbers on the placard on my car. The Pirellis I have are rated for 44 psi max, and I currently have them inflated to about 37-37.5 psi cold. It would probably be too much for someone who is more concerned with comfort than fuel economy.
First, I do understand why vehicle manufacturers specify different recommended cold PSI for front and rear axles on some vehicles.
That said, I would like to know if it is alright to run different front and rear cold pressures on vehicles where the same pressure is recommended, front and rear.
I.E. On my 2015 Hyundai Elantra base model, size P195/65-R15 91T rated tire, the B-pillar placard recommends 33PSI cold, F/R. With both the original Kumhos and the Continentals I currently have on the car, going by that placard produces a slightly rougher than desired ride. Running 32 or 31PSI cold smoothens things out, but my gas mileage drops slightly.
I settled on transferring 1PSI from the rears to the fronts, for 34F/32R, and this gets me the same mileage, roughly, as 33 all around, and tames the rear-end wheel hop enough to enjoy driving more. Elantra steering mode 'Normal' in town, 'Sport'(more driver effort) on highways.
Specifically, my question is: Is it OK to do this? And also, can I increase that differential, up to a point, IE 35F & 31R, for a couple days just to see how it goes?
On my wife's 2005 Toyota Corolla(30F/R cold) I ran 33F/31R, but my wife said it felt like the car was driving nose up a little, like a plane starting to rotate into takeoff. I now keep her's consistently 31PSI F/R year round - no complaints from da wife!
Wow....you must have the most sensitive butt on the planet to notice differences between tires that are +/- 1PSI.
That being said, if it were my car, I would never go below the PSI the door sticker says but going a little over is okay. (Maybe 3-5PSI higher at the most. Any more than that you can start having uneven tire wear, etc.)
So if your car says 33PSI for both front and back, and you don't like that, then maybe try 35PSI front and 33PSI rear.
Depends on the tire, and the car. As NBP mentions, look on the door sticker (assuming the wheels haven't been changed) and don't exceed the max tire pressure listed on the sidewall.
A harder tire is always going to give you better mileage.... however.... the difference between a tire that has 10psi and 20 is going to be huge, between 20 and 30 significant, 30 to whatever diminishing effect with a downward curve.
As they noted in that article they were traveling highways speeds for their test and the higher air friction likely marginalized any gains.
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Originally Posted by iamweasel
Wow....you must have the most sensitive butt on the planet to notice differences between tires that are +/- 1PSI.
That being said, if it were my car, I would never go below the PSI the door sticker says but going a little over is okay. (Maybe 3-5PSI higher at the most. Any more than that you can start having uneven tire wear, etc.)
So if your car says 33PSI for both front and back, and you don't like that, then maybe try 35PSI front and 33PSI rear.
"Wow....you must have the most sensitive
butt on the planet to notice differences between
tires that are +/- 1PSI. "
My keeping her tires at 31PSI have nothing to do with my "butt", and everything to do with keeping her pressures and ride and handling as close to OEM as possible. Thank you.
As per my first sentence in #56, I understand the reasons for F/R tire pressure differentials. Same reason a large van might specify up to 20psi more air in the rear tires than in the fronts(cargo/pax load).
My question again is: Is it OK to run different tire pressures, F/R, on vehicles where the same pressure is listed for front and rear on the vehicle placard?
It probably won't hurt anything, especially if you're not carrying passengers in the rear seat and/or anything heavy in the trunk. My *guess* is that the engineers based tire pressure on the fully loaded weight of each axle. The front axle won't change much, as that's what carries most of the weight of the engine and transmission. The rear axle carries the rear seat occupants and trunk cargo, so if both of those are empty, you should be perfectly safe reducing rear tire pressure by a pound or two.
I would not "transfer" the air pressure from the back to the front, however. I doubt that extra tire pressure is saving you enough fuel to measure. More likely, you had a little head wind when you got less mileage, or there was more traffic, more uphill travel, different roads or different road condition (rain, snow, etc.), different temps, etc. Or, maybe you got an extra quart of fuel in the tank when you got better mileage. I get substantially different mileage on my trips that I take regularly, and I never change tire pressure. My fuel totalizer registered 44.6 yesterday on one of my regular trips (275 miles). Sometimes, on the same trip, it struggles to hit 40 mpg, other times it'll hit maybe 48. Weather and road conditions are the big differences in the variations. Wind plays a huge factor, but since it's always a round trip, not nearly what it would if I went by home to destination and then destination to home.
Other than taking a pound or two out of the rears when you're not carrying rear passengers or rear cargo, it's fairly important for safety to keep them as recommended by that factory so they all hold to the road about the same.
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Quote:
Originally Posted by WyoNewk
It probably won't hurt anything, especially if you're not carrying passengers in the rear seat and/or anything heavy in the trunk. My *guess* is that the engineers based tire pressure on the fully loaded weight of each axle. The front axle won't change much, as that's what carries most of the weight of the engine and transmission. The rear axle carries the rear seat occupants and trunk cargo, so if both of those are empty, you should be perfectly safe reducing rear tire pressure by a pound or two.
I would not "transfer" the air pressure from the back to the front, however. I doubt that extra tire pressure is saving you enough fuel to measure. More likely, you had a little head wind when you got less mileage, or there was more traffic, more uphill travel, different roads or different road condition (rain, snow, etc.), different temps, etc. Or, maybe you got an extra quart of fuel in the tank when you got better mileage. I get substantially different mileage on my trips that I take regularly, and I never change tire pressure. My fuel totalizer registered 44.6 yesterday on one of my regular trips (275 miles). Sometimes, on the same trip, it struggles to hit 40 mpg, other times it'll hit maybe 48. Weather and road conditions are the big differences in the variations. Wind plays a huge factor, but since it's always a round trip, not nearly what it would if I went by home to destination and then destination to home.
Other than taking a pound or two out of the rears when you're not carrying rear passengers or rear cargo, it's fairly important for safety to keep them as recommended by that factory so they all hold to the road about the same.
Thanks for your input! The issue with the 2011-16 Elantra is, at 33psi or higher, the rear wheel hop - at least around where I live, where we pay the highest taxes in America but have roads in worse shape than in Syria presently - is enough to cause me to have to counter steer on occasion. And that's at 30-35mph on local roads, not highways.
Taking 1-2psi out of the rears should not harm things, as long as I don't let any tires on this car go below 30psi cold. And upgrading the rear struts/shocks, as many Elantra owners done, reportedly to great benefit, is not presently in my budget.
As per my first sentence in #56, I understand the reasons for F/R tire pressure differentials. Same reason a large van might specify up to 20psi more air in the rear tires than in the fronts(cargo/pax load).
My question again is: Is it OK to run different tire pressures, F/R, on vehicles where the same pressure is listed for front and rear on the vehicle placard?
Why are you asking this the reason i ask this because are you nit picking this silly question so far just do what is says on the label in your door jamb why do you have to take a simple little thing like tire pressure to the extreme. Just do what the car manufacturer recommend these silly questions are nuts 7 pages on tire pressure.
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Originally Posted by easy62
Why are you asking this the reason i ask this because are you nit picking this silly question so far just do what is says on the label in your door jamb why do you have to take a simple little thing like tire pressure to the extreme. Just do what the car manufacturer recommend these silly questions are nuts 7 pages on tire pressure.
Chill, man...
And of 7 pages my issues occupy only 2. It's a not-so-out-there question, inflating front and rears to different pressures on cars specifying the same pressure all around. People run different front/rear pressures often, even on cars that don't specify such. I've tamed the rear wheel hop somewhat on my 2015 Elantra by lowering the rears to 32psi, and optionally, adding more to the front. I was just concerned about long-term ramifications, if any.
I didn't start this thread, but just thought that bringing up my concerns here instead of starting yet another thread on this topic was the right thing to do.
The correct PSI depends on the car/truck. Generally speaking the pressure listed on the door is a good place to start. This will get you close but you can fine tune it based on your driving style IF you know what you are doing and what to look for.
Two personal examples.
My old Tacoma is running Goodyear "C" load Duratrac's. The Door tells me that the tires should be inflated to 33psi. Difference is that the door assumes that the truck still has "P" rated tires. At 33 PSI the Duratrac's are over inflated, bouncy and only riding on about 50% of the tread face. I used the chalk test to determine the PSI that would give me full contact across the face of the tires. For my truck that is 30psi front and 27psi rear. Tires have close to 27K miles on them with no signs of major wear and the truck handles great. BTW. Max PSI on the side of the tire is 50psi. Way too much for my application but might be perfect for someone running these tires on a 2500HD of F350/450.
Next example is the Eagles F1's on my Camaro. During normal driving leave the tires at the recommended 35psi as shown on the door. When I track the car I pump them up to 40psi. This causes the tire to be more firm and stable in corners.
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