What is the optimum tire pressure?
- Thread starter New18CX5
- Start date
With the stock wheels and tires, I ran 35 psi according to what the door sticker says. After getting aftermarket wheels they're slightly wider and the feel is a bit different at 35 psi. I lowered it to 34 or something and it felt better. Now that I got slightly different size tires, 235/55-19, I run them at 33 psi. I do like the softer ride and my mpg didn't suffer too bad. Question is after tires and wheels have been changed, do we still follow the recommended psi? It took me a lot of tries to finally find the psi that feels good for me, I've tried anything from 33-38 psi on this setup.
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- Plano, Texas, USA
Exactly the same experience here after many years of checking ⋯
I was more than a little concerned to find my tires at 44 psi this evening. I hadn't touched them since buying the car from the dealer a month ago. The recommended psi is 34 here in Canada.
For the record, the car was sitting outside in 6C / 42F weather. There was less than a mile to the gas station where I checked the tires so it wasn't a question of driving for a distance warning them up.
For the record, the car was sitting outside in 6C / 42F weather. There was less than a mile to the gas station where I checked the tires so it wasn't a question of driving for a distance warning them up.
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- Denver, CO
Overfilling has been a common theme it seems from the dealership.
22% over pressure is a bit much tho. I did have a friend whose partner kept inflating his tires to 70 lbs because they didn't look firm enough. I wonder if people just don't understand how tires work.
It's not the dealerships overfilling; it's the dealerships not lowering the psi to the correct levels after shipping. Mazda ships their vehicles with the tires at max psi so they won't get flat spots while they are strapped down on the ship ride over. The service guys that pdi the cars are supposed to drop the pressure but many don't know to.
When I started at the dealership I'm at now, I had to go to management because almost all the vehicles on the lot had their tires 20 psi higher than they were supposed to. Ride quality sucked, and I'm sure some people didn't buy after riding on rocks for their test drives. He told the service manager about it and the next day his guys were out getting the tires to the correct levels
Sadly, this makes sense. Having said that, every air pressure gauge I have owned including the cheapest nastiest ones has a small nib that is used to depress the valve and let air out. I will keep an eye on the tire pressure when I send the car in for maintenance to see what happens.
Yes that is too much but if it's between 1-10 then won't cause too much harm.
One can always lower the pressure.
clownshoes2
2017 CX-5 GT No Tech - 2023 CX-30 GT NA
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- CX-5
The girls must love you at parties....
And your point is......what? I assume that with only 3 posts you are a new member. Anchorman has given very good advice relating to wheels tyres and brakes as he used to work in Research and Development at a well known brake pad manufacturer.
mazdadude
ZOOOOOOOOOM ZOOOOOOOOOM
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- '16.5 Mazda CX-5 Touring
Not just the girls, the guys too! Dude makes an awesome onion dip that's out of this world!
(naughty)
I wish I noticed this earlier. There really is no "ideal" for everybody. The tire placard pressure is the compromise the R&D engineers think most people will like. It applies ONLY to the OEM tires. It is likely a good starting point for other tires.
A mom with a carload of kids in suburbia will want a softer ride and will not be driving fast, so heat is not a problem for her. Her optimum might be 30 psi and absent speed and hard cornering, she'll get good tire life.
At the other extreme, a driver in west TX travelling to distant sales calls, running 10 over the posted 85 mph limit will want much higher pressure so his sidewalls are stiff, reducing heat and increasing control. Pressures over 40 psi will help his tires last longer and be safer.
An autocrosser, the 3rd extreme, is looking for maximum traction and minimum sidewall deflection, so the tread stays as flat on the ground as possible. He will check tire toll-under with chalk on the sidewall and temp across the tread and adjust pressure for the most even temps across the tread. That will likely be 50+ psi. It was for me when running tires that got 32F/30R on the street.
I have winter and summer tires for my Miata. The A/S winter tires are very rough riding, even with Ohlins coilovers. I run them at 26 in the front and 28 in the rear. The placard says 29 psi. My summer tires are Michelin Pilot Super Sports. I run them at 30F/31R. Higher rear pressures are an adjustment to my modified suspension with 25% stiffer rear springs than Ohlins normally supplies. These pressures give both the ride and steering response I like with even tire wear across the tires.
As you can see, What might be "optimum" for me is not for you. As long as you respect the max pressure molded into the sidewalls of the tire and stay above, say 26 psi*, you can run anything you like. Lacking any information to the contrary, begin at the placard pressure and adjust to your liking.
I'm running 36 psi F/R in my OEM 17s.
*I choose this pressure because it was the pressure Ford spec'd for the '90s Explorer that suffered several heat related tire failures. I ran mine at 34F/30R and drove it like my Mustang (i.e. barking the tires in 3rd) without issue.
Hello from Denver.
I have a 2018 CX 5 Touring with 19" wheels and 235/55/R19 101V M+S Michelin Premier LTX tires that I'll be running year round in both highway and mountains.
What confuses me is that the hard copy owner's manual says 35 psi front/rear (p 9-10); however, the on-line owner's manual says 36/36 for up to three people, 38/42 for full load, and for "Winter Tyre" (225/55/R19 99V M+S) 36/39 up to three, and 38/45 full load (wow! my LTX max is only 44).
My Michelins are not dedicated snow tires, but they do carry the M+S label; i.e., good all seasons.
I'll never have more than three people + gear, so what to do - 35/35, 36/36, or 36/39 in winter?
What would you folks do; and, which manual to go by?
Thanks much for your thoughts.
Fred
I have a 2018 CX 5 Touring with 19" wheels and 235/55/R19 101V M+S Michelin Premier LTX tires that I'll be running year round in both highway and mountains.
What confuses me is that the hard copy owner's manual says 35 psi front/rear (p 9-10); however, the on-line owner's manual says 36/36 for up to three people, 38/42 for full load, and for "Winter Tyre" (225/55/R19 99V M+S) 36/39 up to three, and 38/45 full load (wow! my LTX max is only 44).
My Michelins are not dedicated snow tires, but they do carry the M+S label; i.e., good all seasons.
I'll never have more than three people + gear, so what to do - 35/35, 36/36, or 36/39 in winter?
What would you folks do; and, which manual to go by?
Thanks much for your thoughts.
Fred
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- Plano, Texas, USA
Yeah thats why Michelin Premier LTX with low 44 psi maximum inflation pressure is not my top choice for my replacement tire as many modern tires designed to have 51 psi maximum inflation pressure.
Officially Mazda gives US and Canadian customers only one recommended tire pressure, 35 psi for your 2018 CX-5 with 225/55R19 tires. IMO thiss a one-size-fit-all pressure which may not suitable for every different driving conditions. Different tire pressure recommendations for different load and speed, on different tires like you found online should be the one you follow. But remember those recommendations still are just recommendations for OE Toyo A36 225/55R19 tires. Your oversized 235/55/R19 tires would need different psi for optimal performance. I personally put 39~40 psi on my OE 225/55R19 Toyo A23 tires with good result on even wear for 30K miles.
Stumbled onto this thread and decided to check the tire pressure on my newly bought CX-5. On a cold morning, after the car's been sitting all night.. All 4 tires measured ~55 psi!!
Double checked on my air compressor readout and it measured the same. My mistake for trusting the dealership would properly check the tire pressure before delivering the car to me. Haven't really driven it much yet, and it's a good thing I haven't!
A radial tire works by keeping the tread flat and the flex comes from side wall. The tire pressure must be low enough to maintain sidewall flexibility and they is why radials that are run at the correct pressure often look underinflated when they are not. Too much pressure defeats the radial aspect of the tire which is to keep the tread in contact with the road at maximum. Some self-appointed experts still are thinking of the older bias ply tires when they increase tire pressure. Ed
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- 2022 CX-5 Turbo
When we had a Prius, the tires (tyres) were LRR (low-rolling resistance). The side walls were stiff. (hence, LRR)
Running at recommended PSI from Toyota, we saw outer wear on tires. Owners on Prius forum recommended 40PSI or higher. That evened out the wear and save a couple mpgs.
Ride got hasher... a bit.
My point? Many factors to consider... wear, comfort, safety, traction, heavy load ... etc.
contactArea*PSI*4 = vehicleWeight + load
When PSI is low, contactArea increases to balance the equation.
Simple math.
The opposite is true. When PSI increases, contactArea decreases... hence, more wear at the middle of tire treads.
If you carry heavy load, you can increase the PSI to balance it out. Otherwise, contactArea increases (tires look flatter..)
Offroading folks lower PSI to increase contactArea for traction.
On snowy roads also. Good idea to increase contactArea (i.e. lower PSI).
My two cents.
Running at recommended PSI from Toyota, we saw outer wear on tires. Owners on Prius forum recommended 40PSI or higher. That evened out the wear and save a couple mpgs.
Ride got hasher... a bit.
My point? Many factors to consider... wear, comfort, safety, traction, heavy load ... etc.
contactArea*PSI*4 = vehicleWeight + load
When PSI is low, contactArea increases to balance the equation.
Simple math.
The opposite is true. When PSI increases, contactArea decreases... hence, more wear at the middle of tire treads.
If you carry heavy load, you can increase the PSI to balance it out. Otherwise, contactArea increases (tires look flatter..)
Offroading folks lower PSI to increase contactArea for traction.
On snowy roads also. Good idea to increase contactArea (i.e. lower PSI).
My two cents.
