Tire Pressure

mazdaFIVEmike

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2006 Mazda 5 GT 5spd
In the Real World Mileage Numbers thread, we have gone a bit off topic with a discussion around tire pressure to help with gas mileage.

My stock Toyo tires have written on the sidewall that the Max Pressure is 44PSI.

I had stated that I had mine set to 40PSI whereas the dealer always lowers it to 34PSI whenever I'm in for service. The previous tire shop that I purchased my last set of low profile tires assured me that 40PSI was fine.

Any thoughts for the Mazda 5's stock Toyos or general comments???
 
automakers dont arbitrarily pick numbers for the pressure. so unless you have a reason not to, listen to them. they are smarter and agonized over what pressure to spec more than you could imagine.
 
Historically, I've always upped the tire pressure by a couple of pounds from the manufacture's recommend setting.

I've found that it gives me a little better mpg and slightly sharper handling.

However, with the 5, the handling is already pretty sweet at the manufacture's setting, so I've left it alone.

I think the max tire pressure listed on the sidewall of the tire is the max pressure before the tire could/will explode. However, I don't know if that is the "cold" or "hot" pressure.
 
mazdaFIVEmike said:
In the Real World Mileage Numbers thread, we have gone a bit off topic with a discussion around tire pressure to help with gas mileage.

My stock Toyo tires have written on the sidewall that the Max Pressure is 44PSI.

I had stated that I had mine set to 40PSI whereas the dealer always lowers it to 34PSI whenever I'm in for service. The previous tire shop that I purchased my last set of low profile tires assured me that 40PSI was fine.

Any thoughts for the Mazda 5's stock Toyos or general comments???

Usual rule of thumb is to follow the numbers on the stickers (driver side door). The manufacturer have tested it and those are the numbers they came up with which worked best for comfort, handling, fuel mileage. However having said that, you can add a subtract a little, for eg. someone who drive real aggresive and wants better response during turns, he would add maybe 2 psi to it. But by adding 2psi, your ride is slightly harsher, so in essense one has sacrificed comfort for handling. But don't go overboard with adding or subtracting psi, this will compromise safety (during braking) and cause premature wear (either inside or outside of tire depending on too much or too little psi). Also the tire pressure is measured when the tires are cold ( I think not used for at least 3 hours.)

Cheers
 
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canadianexpress said:
Usual rule of thumb is to follow the numbers on the stickers (driver side door). The manufacturer have tested it and those are the numbers they came up with which worked best for comfort, handling, fuel mileage. However having said that, you can add a subtract a little, for eg. someone who drive real aggresive and wants better response during turns, he would add maybe 2 psi to it. But by adding 2psi, your ride is slightly harsher, so in essense one has sacrificed comfort for handling. But don't go overboard with adding or subtracting psi, this will compromise safety (during braking) and cause premature wear (either inside or outside of tire depending on too much or too little psi). Also the tire pressure is measured when the tires are cold ( I think not used for at least 3 hours.)

Cheers

I agree, 2PSI here or there is not going to make or break you. The vehicle manufacturer has to weigh all the factors to arrive at the perfect balance (pardon the pun) for that particular tire on that particular vehicle. However, I also trust the tire manufacturer when they advise on tire pressure. Its a fine line between what's best for the vehicle and what's best for the tire. So far I've had no problems with it set at 40 and I've got over 10000km and at my last service - tire check and rotation was part of that - and there were no problems reported. Of course if I was to load the car up with gear and people on a hot summer day I would need to confirm I was still around the 40 mark before heading out.
 
2 psi UNDER the mfg spec pressure has shown to give up to a 10% drop in mileage. plus underinflation makes your tires wear faster.
 
Most of us are talking about 2psi under 'max' not recommended psi. My last 3 cars have always been 2psi under 'max' both done by dealers so I;m assuming 2psi under is acceptable. If I'm wrong it's because I've been conditioned incorrectly :)
 
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i wouldnt set it that close to your max psi. a rule of thumb is a 1 psi increase for every 10 deg F in temp increase. So if you set 2 psi under in the dealers garage at 70 psi, youre at max on a 90 deg day, not to mention that your tires heat up (a lot) while driving. plus, going that high can cause irregular wear and tire damage over time.
 
yea, I thought recommended tire pressure was on the door sill. Not on the tire. Because the tire can be for other cars too, that weigh differently. The # on the door sill is specifically for your car, thus its the recommended pressure.
 
Well, not 2 exactly, I just used that number because my last 3 cars were all average 2 psi under the max which was usually the same as the recommended number except for my Jetta which seemed to want under inflated rears (or was it fronts)
 
Kid Red said:
Well, not 2 exactly, I just used that number because my last 3 cars were all average 2 psi under the max which was usually the same as the recommended number except for my Jetta which seemed to want under inflated rears (or was it fronts)


Hey Kid Red
I'm sure my Jetta recommended 32psi all around. Tires said max 44psi and its when I purchased new tires that the tire shop set them at 40psi.

Needless to say I was shocked when I checked the pressure one day and called them immediately. I really didn't notice that much difference in the ride but I did notice that I got consistantly 450km+ out of a tank of gas instead of the 400km I got before the new tires (and new pressure setting)

In the 3 years after setting the pressure to 40psi - I never had a problem with the tires, handling or ride.
 
mazdaFIVEmike - Thanks for this thread.

For what it's worth here are some links about tire pressure.
http://www.betiresmart.ca/inflation/proper.asp?loc1=inflation&loc2=proper
http://cars.cartalk.com/content/advice/tirepressure.html
http://www.edmunds.com/ownership/safety/articles/100811/article.html
http://home.hamptonroads.com/stories/story.cfm?story=97426&ran=210871

Seems the bottom line is over inflating your tires means less tread to road contact, which is a safety concern (e.g. it can increase breaking distances).
Underinflation reduces mileage and can cause tire failure.
 
Fly on the Wall said:
mazdaFIVEmike - Thanks for this thread.

For what it's worth here are some links about tire pressure.
http://www.betiresmart.ca/inflation/proper.asp?loc1=inflation&loc2=proper
http://cars.cartalk.com/content/advice/tirepressure.html
http://www.edmunds.com/ownership/safety/articles/100811/article.html
http://home.hamptonroads.com/stories/story.cfm?story=97426&ran=210871

Seems the bottom line is over inflating your tires means less tread to road contact, which is a safety concern (e.g. it can increase breaking distances).
Underinflation reduces mileage and can cause tire failure.

Excellent links Fly!
Thanks
 
The rule of thumb I've always followed with tires is to set them at the exact psi as stated on the door sill when they are cold...They tires will tend to heat up and expand up to 2psi on hot days and over the course of extended driving periods...For those who like that stiffer ride and crisper handling, you'll likely get it with your tires set at the dealer recommended psi :)
 
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Depends how you drive!

I believe the correct pressure depends on your driving style. If you drive like the owners manual suggests then by all means follow the specified pressures. However, if you drive a little faster in the corners then you'll need more pressure to prevent the tires from "rolling" and wearing the edges. I run my protege at 40 front and 35 rear and when the tire are worn out they are worn flat all the way across.
 
WHOA!!!!

So after all of this tire pressure talk I decided to head outside to check the pressure in my tires...I've had my MZ5 now for about two months and am heading on a long road trip in a couple days so I thought it wouldn't hurt to up to par pressure wise...Afterall, I never checked the PSI settings since I drove it home from the dealership...

Both rear tires were set at 45PSI, while he front left tire was at 46PSI and the front right tire was at 48PSI!!! Jeebus man was the dealership trying to kill me and my family!!! Every tire was overinflated and these readings were taken with a digital gauge, and the car hasn't been driven since yesterday evening...

No wonder I was getting a bit of a drift at high speeds and wobbly cornering when at high speeds on the freeway...They're all set at 36PSI (which should be more than acceptable), and I'll be posting again with the handling and steering response now that they are where they should be...

***Edit***

Alrighty, I dropped the tires down to 36 psi each at cold temp. and the ride was way too gummy...The acceleration got notchy and hesitant, the steering was less responsive, and there was significant torque steer at accelerating from a dead stop and also when braking...I never experienced the grab when braking before so I had to attribute it to the new psi settings...Once the tires warmed up, I checked the pressure again and it rose to 37psi per tire...With thee ride still nowhere near where I wanted it, I added more air when they were still hot increasing the psi to an even 40psi per tire...

All problems seemed to be solved...Not only do I have a much more smoother and softer ride than I did before I began changing the settings, but the road noise has been cut down some, and braking & steering are responding perfectly again...In fact, the steering is a lot tighter now and there seems to be a good amount of traction...I road tested the new psi settings through the winding hillsides that aurround our house this evening and it took the corners like a pro...I am still experiencing slight torque grab when taking off from a stop when I give it a lot of gas, but thats to be expected in this type of car, and I've always had this...However, the grab when braking is completely gone now so thats a bonus :)
 
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7red7 said:
WHOA!!!!

So after all of this tire pressure talk I decided to head outside to check the pressure in my tires...I've had my MZ5 now for about two months and am heading on a long road trip in a couple days so I thought it wouldn't hurt to up to par pressure wise...Afterall, I never checked the PSI settings since I drove it home from the dealership...

Both rear tires were set at 45PSI, while he front left tire was at 46PSI and the front right tire was at 48PSI!!! Jeebus man was the dealership trying to kill me and my family!!! Every tire was overinflated and these readings were taken with a digital gauge, and the car hasn't been driven since yesterday evening...

No wonder I was getting a bit of a drift at high speeds and wobbly cornering when at high speeds on the freeway...They're all set at 36PSI (which should be more than acceptable), and I'll be posting again with the handling and steering response now that they are where they should be...

***Edit***

Alrighty, I dropped the tires down to 36 psi each at cold temp. and the ride was way too gummy...The acceleration got notchy and hesitant, the steering was less responsive, and there was significant torque steer at accelerating from a dead stop and also when braking...I never experienced the grab when braking before so I had to attribute it to the new psi settings...Once the tires warmed up, I checked the pressure again and it rose to 37psi per tire...With thee ride still nowhere near where I wanted it, I added more air when they were still hot increasing the psi to an even 40psi per tire...

All problems seemed to be solved...Not only do I have a much more smoother and softer ride than I did before I began changing the settings, but the road noise has been cut down some, and braking & steering are responding perfectly again...In fact, the steering is a lot tighter now and there seems to be a good amount of traction...I road tested the new psi settings through the winding hillsides that aurround our house this evening and it took the corners like a pro...I am still experiencing slight torque grab when taking off from a stop when I give it a lot of gas, but thats to be expected in this type of car, and I've always had this...However, the grab when braking is completely gone now so thats a bonus :)

What's your background 7Red7? That's quite the detailed description of the differences in handling with different tire pressures that you've given. Just wondering... not trying to put you on the spot or anything. I know from my personal experience that I can notice a difference but couldn't specifically point out those particular attributes.
 
just look on your inside door panel or on the body frame by the drivers door with your vin lable there will be a lable for tire information. Check it and adjust accordingly.
 
mazdaFIVEmike said:
What's your background 7Red7? That's quite the detailed description of the differences in handling with different tire pressures that you've given. Just wondering... not trying to put you on the spot or anything. I know from my personal experience that I can notice a difference but couldn't specifically point out those particular attributes.

Oh no worries :D I'm not a mechanic or anything, but I've had a good deal of problems with tires, allignments, and tire pressure settings with previous cars...Buy a Hyundai you'll know what I mean ;) I've kind of learned what to look for with a car's handling, takeoff, and braking by asking my father a lot of questions: He was a mechanic with Ford Racing in the past...

Slightly off topic - I have read a lot of posts on other forums where people are really putting down the stock Toyo Proxes that come stock on our Mazdas, but in reality, these are excellent all season performance tires that were made for touring conditions...With the right settings you can get an amazing ride out of them...I love our stock tires!!! :D

HAPPY DRIVING!!!

DAN
 
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