Tire pressure

[Mike72771]

Hi guys,

I have a silly question that I popped in a search and came up with nada.
I just bought a Mazda3 5 –Door. I've been driving SUV's for the past ten years and I'm a little out of the loop as far as little car handling.

The recommended PSI on the door is 32 I think it feels squishy but that could just be the result of me being used to the ride of a truck. I noticed the dealer had the max PSI of 45 on all four tires. Question is should I go with the door sticker or fill it back up to max PSI?

What would you all suggest?

Mike

[crossbow]

Gah!!! Don't drive around at max psi!!!

First try setting the PSI at 32 (as per factory specs). If you don't like that, try 34-36. A little bit more psi will stiffen the ride up a bit, but reduce sidewall rollover in a harsh turn, and also reinforce the sidewalls a bit against bumps/potholes.

Going from 45 to 32 will most likely not only increase your traction, but greatly increase your ride comfort.

I'd investigate finding another dealership, cause overinflating your tires to 45 says volumes about their competence.

[wongpres]

The cars are shipped from the factory with very high pressures, like 45PSI, to avoid flatspotting during transport (this applies to most cars, not just the Mazda3). Dealers are supposed to lower them back to the appropriate pressures during the car's PDI. Some dealers forget to do this, and so customers may notice their vehicle having such high pressures.

Be near the PSI levels on the door sticker.

[Mike72771]

Thanks for the replies guys.

I dropped the pressure to 32 when I took delivery on Saturday. I’ll leave it at 32 PSI and tool around for a few days. I will do my best to avoid potholes, I used to aim for them in the truck (lol2) (wrc)

[ham]

I'd suggest following the door plate psi rating very closely and checking the pressure monthly while the tires are cold (i.e. after the vehicle has been sitting for a few hours). Low pressure not only causes early wear and increases failure rates - it also negatively impacts fuel consumption. Overinflating your tires can also cause problems greater than just a harsh ride - failure rates increase as you hit more potholes, etc on overinflated tires and you will scrub tread unnecessarily when cornering - thus reducing the life of your rubber.

If your tires are already at max pressure when cold - remember that as soon as you start driving - the heat of the road friction will further increase the tire pressure beyond max.

ham


Hi guys,

I have a silly question that I popped in a search and came up with nada.
I just bought a Mazda3 5 –Door. I've been driving SUV's for the past ten years and I'm a little out of the loop as far as little car handling.

The recommended PSI on the door is 32 I think it feels squishy but that could just be the result of me being used to the ride of a truck. I noticed the dealer had the max PSI of 45 on all four tires. Question is should I go with the door sticker or fill it back up to max PSI?

What would you all suggest?

Mike

[Mikey444]

I have mine at 35 psi but I a, going to get them up to 37, I dont like the way they ride at 35.

[crossbow]

The higher the pressure...the stiffer the sidewalls, and lesser the ride quality. If you want to improve ride quality, reduce the pressure, don't increase it.

[Mikey444]

The higher the pressure...the stiffer the sidewalls, and lesser the ride quality. If you want to improve ride quality, reduce the pressure, don't increase it.
I know what you are saying, but I dont like how soft the feel is ojn the road at 35 PSI, at 37 PSI it has that nice stiff feel and I feel a lot more comfortable a=on curves and by the way it seems to drive a lil better at 37 PSI

[crossbow]

Aye. Didn't know what you were looking for. Do note that too much pressure will reduce your overall grip...finding the exact right pressure is key.

Under aggressive driving, you can increase the pressure as much as 4-7 psi!!!! (As the tires heat up) Thats why you'll see autox'ers usually RELEASING pressure after a run, to try and equalize it out, and prevent excessive understeer (plowing) caused by excessive pressure.

[El Ropo]

Oh well, I'll chime in since my angle hasn't been mentioned yet. With a Front wheel drive car, most of the weight, and abuse happens with the two front tires. Because they are doing the accelerating, much of the braking, and most of the turning. I Always run with a higher pressure in the front tires, than in the back. In my MZ3 Hatch, I'm running 37ish (PSI Cold) in front, and 32ish (PSI Cold) in rear. When the tires get rotated, I'll go around and readjust them all again to my liking. And NEVER TRUST YOUR SERVICE PEOPLE TO GET IT RIGHT.

When getting my tires rotated on my last car, I'd specify pressures I wanted the tires at, but they would never do it right. Also, every time I've gotten brand new tires installed, they would never inflate the tires to the correct pressures, always leave them around 25 PSI. I think they do this on purpose so the tires wear out quicker, and they can claim abuse for underinflation and void the warranty.

[gino]

Running 205/40/17s on the P5 and wife's ES. Goodyear F1 GS-D3s and Kumho ASXs. Both cars at 35 psi all around. Excellent handling, good ride and no excessive wear.

[Mikey444]

I agree with El Ropo on every point.

[sndsgood]

i run 125 in front and 100 in back

[crossbow]

Always good to insert useless and pointless information into an informative thread. Its like snail racing...nobody really cares.

[3Wheeler]

Just wanted to jump in with a few things.

First, the manual (p.111) says to inflate snow tires an extra 4.3 psi over the door placard. Is this just because they assume the air temp is going to be colder, making for less psi? (I note they also say not to go over 75mph on snow tires....but surely it depends on the snow tires' speed rating. Mine are v-rated, and I can vouch for them feeling very good at speeds well over 75mph.)

Second, I've dealt with two tire dealerships over the last few months (long story), and both insisted that I'd get better tire performance if I ignored the door psi and ran at "at least" 40 psi. After researching the issue on the net, I ignored them and run at door psi or a little higher. I've got my Yoki AVS Winters at 37 all round now (as per manual's add 4.3psi), and they feel great. It's weird though that the supposed tire "pros" give advice that's completely contrary to what the tire manufacturers say.

Finally, some people say you should adjust your psi so that a chalk line drawn across the tread wears evenly after you drive the car a hundred feet or so. Comments, anyone?
--Barry

[Mikey444]

Aye. Didn't know what you were looking for. Do note that too much pressure will reduce your overall grip...finding the exact right pressure is key.

Under aggressive driving, you can increase the pressure as much as 4-7 psi!!!! (As the tires heat up) Thats why you'll see autox'ers usually RELEASING pressure after a run, to try and equalize it out, and prevent excessive understeer (plowing) caused by excessive pressure.
I ended up inflating all 4 tires to 36 PSI and 3 things happened:

- the tires had better grip

- they stopped wearing out like crazy

- Better handling all around.

It's quite amazing how much just 1 psi of pressure does all the difference.

[Rock]

Ok guys I'll let you know how to go about setting your tire pressure.
#1 rule is ALWAYS start off with what the door placard recommends as the tire pressure. There's a reason they recommend that pressure, and it's more than likely to be what they figured as the perfect medium( tire wear, total grip, ride comfort). Of course everyone isn't the same and so tire pressure can be changed accordingly. Now let me tell you that going 2-7psi over the recommended inflation numbers will not DRASTICALLY affect tire wear, but will eventually affect it towards the end of a tire's lifespan( i.e within last 2rotations; approx 5-8kmi. per rotation). Pay attention to the maximum inflation pressure on your tires, some are maxxed out at 35PSI while others max out around 45psi. the closer you are to max tire pressure you are the higher the risk of failure either from being out of round, uneven wear, or seperation.( Warning: this happens over time, effects are not noticeable immediately). there are many GOOD effects of running a higher pressure and most of them have been stated, but I wish to disagree with crossbow on the handling decrease on tires with higher pressure. Your handling WILL increase up to a certain point, but will decrease when you go past it. ALL tires have a increase point and decrease point ( if you understand what I'm saying). For example, FALCON tires LOVE higher pressure at around 36-40psi range, but after that they seem to decrease in grip/handling. Yokohamas on the other hand LOVE being around lower pressure 32-36psi. See my point?
ALL I can say is stay within the recommended tire pressure for door placard, but also experiment with your tire pressures while being in a safe limit.
NEVER EVER UNDERINFLATE YOUR TIRES, UNLESS YOU ARE DRAG RACING.

RECOMMENDED TIRE PRESSURE: 32 SAFE INFLATION AREA: 32-37

[Mikey444]

I dont mean to thread Jack, but on my Mazda 6 I have Michelin rubber, the recomended on the sticker of the door says 32 PSI, they seem to soft and slip a lot. I checked and all 4 were at 32 exactly. Now should I inflate them slightly, 1 or 2 psi? Secondly, 32 to me sounds low, is this close too close to an unsafe limit despite what the sticker says. I mean stickers arent always right despite numerous tests.

[3Wheeler]

Thanks, Rock.

What if you go to a different size tire than stock? Does the door placard's recommended psi still stand? For example, what if you plus sized to a tire with a higher load rating?

[Rock]

As far as plus sizing and higher load range tires go you usually increase the tire pressure to keep the tires within a safe limit esp to keep the sidewalls stiffer.
For example: Mazda3 5dr w/ 17 inch wheels with 205/45/17 = 32psi
(according to the door placard)
Plus size to 18 inch wheel w/ 225/40/18 = 35psi

same deal with high load range tires. .. . . . .....

Your local tire store should have a Load index range sheet that'll show the load range + tire size = psi

[carperformance3]

okay, i've been toying around with my tire pressures on my 3 for the last 3 or 4 months, but i've by far made the most progression today, when i went autocrossing for the 2nd time. granted some people don't want their car set up for maximum performance at any cost, and different courses will warrent slightly different tire pressure needs. but i found a very useful tire pressure setting. if any of you have heard of putting shoe polish on your sidewalls to watch rollover, this is how i found my pressure. wanting to save my all-season tires from the destruction of autoxing i started today with 42.5 in the front, and 41 in the rear. if you look on the corners of your tires there is a little arrow every so many grooves. when you put the shoe polish on, your goal is to get the tires to rollover to the tip of that arrow. any more rollover than that, and its counter productive. so what i found in my testing today, my final tire pressure (when hot), was 46 psi in the front, and 34 psi in the rear. yes, you read that right, very drastic, but without suspension mods, the rear just doesn't do a whole lot on the 3 other than hold on. i actually could have gotten away with even lower pressure in the rear, but that was my last run, and i was dropping them about 2 psi per run (versus start of previous run). if you doubt my credibility on these numbers, i beat two sti's, one of them modified, a heavily modified s2000, about 2 seconds behind a heavily modified evo, and i beat my friend in an integra type r. and all i have is an intake. those pressures when cold, based on the amount of air i released from the front (which were still rolling over too much) would be sitting about 42 cold, and about 30 in the rear. i'm not done playing yet, although i must admit, i did drop my front tire pressure some when i left, because i noticed the center of my tread wearing faster than the corners (surprisingly). more or less the moral of the story is if you want max performance by adjusting your tire pressure (cheapest way to get it), you're going to want some pretty drastic pressure differances.