CX9 Tyre pressures

clarko

Member
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Mazda SP23 and CX9
We all know that all cars come with a plaque with the so called correct tyre pressures on it, but I have always found the need to increase this figure a fair bit for optimum performance, I don't mind sacrificing a little comfort for a better steering car.
I have always been fussy with my tyre pressures, but I have been having so much fun with the rest of my 9 that I had forgotten about re-adjusting tyre pressures until the other day when I was towing my boat I noticed the back tyres looked a little flat, then I realised that it was in getting the 1000k check over from the dealer the week before and they must have adjusted the pressures. I then put the gauge on them and found all 4 wheels had exactly 32psi in them.
Mine has the 20" wheels, but would be interested to hear from all, what pressures you run in your CX9, and that can be for both 18 & 20" wheels.
Maybe then I can take an average of all and come up with the best tyre pressure.(2thumbs)
 
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You know I haven't even checked the tyre pressures in the 3 months I've owned my CX-9. They do look OK but I really should check them I suppose. I should check the plate too because at the moment I have no idea what the recommended pressures are either.
 
We all know that all cars come with a plaque with the so called correct tyre pressures on it, but I have always found the need to increase this figure a fair bit for optimum performance, I don't mind sacrificing a little comfort for a better steering car.
I have always been fussy with my tyre pressures, but I have been having so much fun with the rest of my 9 that I had forgotten about re-adjusting tyre pressures until the other day when I was towing my boat I noticed the back tyres looked a little flat, then I realised that it was in getting the 1000k check over from the dealer the week before and they must have adjusted the pressures. I then put the gauge on them and found all 4 wheels had exactly 32lb in them.
Mine has the 20" wheels, but would be interested to hear from all, what pressures you run in your CX9, and that can be for both 18 & 20" wheels.
Maybe then I can take an average of all and come up with the best tyre pressure.(2thumbs)

U.S. placard says 34/34 psi f/r. The tires have a max rating of 51 psi and I'm running mine at 41 psi f/r. It definitely makes the vehicle handle better running the higher psi, not to mention it assists in reducing rolling resistance to help the mileage a bit.

Ted
 
I pumped all of mine up to 40psi yesterday and found it turned into the corners much better, yet I did not even notice any difference in the ride.
Also feels lighter at parking speed.
 
Just watch for excessive wear in the centre of the tyre if you are going to overinflate them. It's not usually too much of a problem though as most tyres tend to wear on the edges first due to mis-alignment.
 
Higher tire pressure may provide harsher ride

I have the GT AWD with the 20" wheels as well. For the first 2 weeks of ownership, I found that the ride was a little harsh on bumpy roads, which we have plently in the Bay Area (California). I then checked the tire pressure and found that it was 42 psi on all 4 wheels. Since then I lowered it to 36 psi and found the ride was smoother over the bumps. However, I forgot how it handled previously with the overinflated tires so I cannot tell if handling is any different. I may bump up the pressure to 39 and see how that may work. By the way, the pressure I am quoting here is when the tires are cold. I found the pressure will increase 4 to 5 psi when they were hot.
 
By the way, the pressure I am quoting here is when the tires are cold. I found the pressure will increase 4 to 5 psi when they were hot.


Thats a worthy point, my pressures were read after driving around for an hour, so I guess my 40psi would be when hot. That also means the 32psi the dealers did would be somewhat even less when cold, no wonder it felt spongy.
 
I run 36psi all round when tyres are cold.
I find that I have to check my tyre pressures every month because even a difference of 5psi tends to make my CX9 steering slightly pull to the side.
 
The thing to keep in mind is that manufacturers typically set tire pressures to maximize the ride quality, not optimize the handling. So inflating the tires to a higher pressure isn't necessarily over-inflating them.

That said, one definitely doesn't want to inflate them such that they'll be near the max inflation pressure when hot. That's why I usually check my tires both cold and hot to see what that range is.

Running these tires in the high 30's and low 40's psi range shouldn't present any problems with excessive wear.

Ted
 
My CX-9 was delivered with 45psi in each (18") tire, and it was loud, stiff and uncomfortable. I brought them down to 32psi, and it drives like a dream. If I was carrying any load, or summer time road trip at 110F, I would definately put up to 40psi.
 
When I brought home my CX9 Touring the tires were inflated to around 38/39 psi. Right now I'm driving at the recommended 36 psi. There are certain bumps that cause a "jarring" feeling when you drive over them whichs tend to ruin an otherwise pleasant ride. I've thought about lowering the pressure down to 32 psi but with it being winter I'm afraid that the pressure will get too low with the temperature fluctuations.
 
I was once informed by an alignment shop that a national tire sales and installation company purposely under inflate the tires not only at the sale, but each time you bring it in for the rotation and balance...he said this is to make them wear faster, thus more new sales sooner.

Any comments?
 
I was once informed by an alignment shop that a national tire sales and installation company purposely under inflate the tires not only at the sale, but each time you bring it in for the rotation and balance...he said this is to make them wear faster, thus more new sales sooner.

Any comments?

No way is any tire company going to do this. There would be way too much liability if a blow out and accident occurred.
 
Psi

I run 42 PSI (cold) on my 20" Duellers. Seems right. A little rough over sharp bumps, but hey, they're low profile 20 inchers. Wasn't looking for a posh ride nor for auto cross performance - somewhere in betweeen seems reasonable.

Life is too short for high mileage tires.
(hahaspit)
 
I had a play around with the tyre pressues for the last two weeks. My findings were: at 33PSI as recommended, the car felt very sloppy. Bodyroll was a lot more evident, steering felt a lot less connected and it might be subjective, but it felt as if the acceleration had been dampened. However the ride was a LOT softer. Couldn't really feel any bumps in the road, but according to my passengers, the car felt a bit floaty at high speeds which made a few people nauseous which has never happened before. Reading the trip computer, i found that fuel economy was also slightly higher than usual. I didn't really enjoy driving with 33PSI.

Next 4 days i increased pressues to 36PSI. Steering, handling, bodyroll and acceleration were vastly better than when the tyres were at 33PSI. What amazed me was that ride quality wasn't compromised as much as i thought it would be. It still felt just as smooth as 33PSI and i honestly think it would be hard to feel the difference driving over a bumpy road at 33 and 36PSI. Even if there was a difference in ride quality, i would much rather sacrifice it for better handling, steering, body control and fuel economy.

Since then i've increased tyre pressures up to 38PSI. Not much difference in fuel economy or handling, but you do feel a lot more bumps through the suspension. They're still at 38PSI, but im thinking about dropping it back down to 36PSI.

36 seems to be the magic number for CX9's running the 20" wheels, despite what Mazda recommends.

What is everyone else running and what are your experiences with different tyre pressures? State your wheel size as well.
 
I had a play around with the tyre pressues for the last two weeks. My findings were: at 33PSI as recommended, the car felt very sloppy. Bodyroll was a lot more evident, steering felt a lot less connected and it might be subjective, but it felt as if the acceleration had been dampened. However the ride was a LOT softer. Couldn't really feel any bumps in the road, but according to my passengers, the car felt a bit floaty at high speeds which made a few people nauseous which has never happened before. Reading the trip computer, i found that fuel economy was also slightly higher than usual. I didn't really enjoy driving with 33PSI.

Next 4 days i increased pressues to 36PSI. Steering, handling, bodyroll and acceleration were vastly better than when the tyres were at 33PSI. What amazed me was that ride quality wasn't compromised as much as i thought it would be. It still felt just as smooth as 33PSI and i honestly think it would be hard to feel the difference driving over a bumpy road at 33 and 36PSI. Even if there was a difference in ride quality, i would much rather sacrifice it for better handling, steering, body control and fuel economy.

Since then i've increased tyre pressures up to 38PSI. Not much difference in fuel economy or handling, but you do feel a lot more bumps through the suspension. They're still at 38PSI, but im thinking about dropping it back down to 36PSI.

36 seems to be the magic number for CX9's running the 20" wheels, despite what Mazda recommends.

What is everyone else running and what are your experiences with different tyre pressures? State your wheel size as well.

Thanks for the excellent feedback. I appreciate you taking the time to tell us of your testing and experience.
I usually carry a load of literature and samples in the "way" back (third row is flat) so I'll kick my rears down to 38 and my fronts to 36 and see how it feels.
Again, thanks!
 
I'm sticking with 34 these days. I ran a couple psi higher on my last tire set and they had some cupping by the time I replaced them, not real bad, but obviously wore out faster in the middle due to over-inflation.
 
I like to run my tires a little hard too - a compromise between ride quality, cornering capability and fuel consumption - so I am at 36 right now and
I am new to the vehicle. I'll be watching for the cupping issue but it's only 2 pounds. The other factor would be aquaplaning as the grooves might not be so efficient at moving the water from under the tire at a higher pressure.
 
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