Over inflated tyres

[NitroDann]

One of those guys..

I bet you run the OEM tyre also right, to match the OEM pressure?

Ok.

[Odd]

Yep

But it makes sense if you run wider tyres....you pump them up so they have same width of tread on the road as a OEM tyre

[Dan]

Did you ever consider that the driver might have something to do with the car understeering?

When you said that you were "braking INTO a corner" I immediately thought driver error, braking into a corner will cause understeer. Your braking should be done before the corner.

I agree with Dann though on pressures, one person's skittish is anouther persons responsive..

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[pepejesus]

That's the difference.....

Mazda has ENGINEERED a car

Others chose to add significantly more power, increase wheel sizes and widths...increasing rolling diameter and track, lower the car and change suspension, changing the suspension geometry and You can increase tyre pressure to taste

Lovely.....but....It's no longer Engineered....it's modified and in most cases, more than likely....illegal

I'm more than Happy for others to take their chances and make their changes....just not with my car without my knowledge

So just bleed out some air until you've got 26psi then? And just tell the workshop what pressure you want next time?

36psi is not dangerous and is a pretty typical pressure to run on the street, as many others on this thread can concur.

What actually happened in this understeer moment - did you run off the road?

[Odd]

If someone can link me to a tyre manufacturer or Mazda web site that says over-inflating tyres by 37% is perfectly safe and... even recommended....then I have no case

It seems.....No doubt lots of people Love to over-inflate their tyres.....that's not proof that it's safe....its just proof that lots of people do it

dríven this car for 2 years.....been running tyres at 26psi.....NEVER had any hint of understeer....just odd Occassion of oversteer in the wet
Perhaps my technique wasn't perfect.....but that's what is great about this car....it is very forgiving
Soon as I backed off it turned the corner....but I didn't like it the initial understeer
I wasn't exceeding the speed limit....or driving on the edge
The only thing different....that I didn't find out till later....was the tyre pressure

Everyone can make their own decision.....and if someone reads this and then checks their tyre pressure....that's great
Better that everyone makes their own decision.....and not just leave it to the kid at the service centre who hasn't read the label on the door....;)

[NitroDann]

Better that everyone makes their own decision.....and not just leave it to the kid at the service centre

There is something we can agree on.

[1green5]

Yes, you under-steered because your tyres had too much pressure in them.

Now you've gotten the answer you wanted, let's move on.

[project.r.racing]

Seems logical to me that a Light car with 2 passengers would need less pressure in the tyres than a heavy car carrying 4 passengers
NA8 is 980kg ....recommended tyre pressure...26psi
Cx5 is 1627kg.....recommended tyre pressure...34psi
Running a NA8 @ 36psi cold is like running a CX5 @ 47psi cold....which is...in reality....ridiculous

That's the difference.....

Mazda has ENGINEERED a car

Dont compare apples and oranges. Comparing a car engineered in the 80s to another car engineered 25+ years later isn't good science.

Many things have changed over that 25+ years. I'd suggest most of you arguement and bias are based on a tyre placard printed in 1990.

Do you still put 10W-30 mineral oil in the engine as that is what they suggested in the owners handbook from 1990? Or you you run a different weight semi or full synthetic nowadays?

p.s. I also see a problem within this thread. You posting is in reaction to what others have said they put into their tyres. But no one actually has the tyres you have that have posted. They are all bigger and wider tyres. You could put 28 or 30 in your 185/60R14s with issues.

[93_Clubman]

a tyre manufacturer...that says over-inflating tyres...is perfectly safe and even recommended

Context, context, context - Oscar Pereda, a tyre engineer for BF Goodrich advised: "There is no 'golden' tire pressure." "The optimal setting depends on the individual driver and his preferences."
Anyone that's done an advanced driving course is highly likely to have been advised to run at least 32PSI cold on road. Personally, on road my NA8 runs 32PSI cold.

[Odd]

I'm sure Mazda recommend 26psi for a sound engineering reason
I've tried 36psi in my Tyres....and I don't like it

I'm sure there would be a point where grip and stopping ability is compromised by increased tyre pressure

but I haven't been able to locate any published results...all tests seem to focus on under inflated Tyres

so in the end it is a matter of preference....logic?
Seems None run lower pressure...but up to 20% increase is common

If I ever decide to carry a small elephant in my boot.....I'll increase my tyre pressure....until then I remain unconvinced that 36psi in my Tyres is a Good idea
but I do acknowledge 26psi isn't a Golden rule

Thanks for the opinions ;)

[NitroDann]

Many people run lower pressure, every person who has ever owned a 4wd knows that on some surfaces and conditions, as low at 10psi is recommended, and thats with your normal tyres many 4wd's have, competition 4wd tyres go even lower.

I suspect the 26 recommendation has to do with ride comfort, given that the car has such a light body which is affected by small bumps much more than a heavier bodied car.

Dann

[Odd]

Sure....drop tyre pressure on 4x4's once you hit the sand and in older models lock the front hubs....but pump them up again before you go back on the bitumen....and unlock the hubs....increase tyre pressure if you are loaded to gunnels or towing caravan/boat...
Owned plenty of off-road vehicles....
Not planning to take the NA8 up the beach or towing anything with it ;)

[shortSteve]

Wow. So much heated debate over opinions?
Ok, so tyres have a maximum inflation pressure, for load and speed, that is far higher than manufacturer recommendations, which are all based around ride comfort and "safe handling" (understeer usually, so usually upping the pressure will result in more responsive direction change, better edge grip/bite but a firmer ride. There is a point it goes too far, and then overall grip will deteriorate, but balance won't change (assuming equal pressure adjusted).
Maybe I am old school, and chase a 4 psi increase of cold pressures on road or tune to hot/useable temps on track. If pushing harder, I measure carcass and tread temps with a heat gun. For my road going radials around 70-80 degrees seems to be the fine line between grip and squirm, or slide of colder. On (short) track, 29 seems about right (happens to be manufacturer recommended to), on the road however 31-2 seems to be better, despite lower carcass temps. Longer tracks with higher speed corners, I could imagine lower again, but only if getting the heat into it, otherwise side walls would just roll under the carcass...
Each to their own tho

[93_Clubman]

I'm sure Mazda recommend 26psi for a sound engineering reason
Thanks for the opinions ;)

Thanks for your opinion, because apart from the fact that Mazda recommend 26psi all round for an NA8, the rest is opinion. And no one's telling you to run your tyres at 36PSI cold.
Btw, most cars, like most things, are a compromise.

[hks_kansei]

would be worth adding, the comments about tyre wear arent as important these days with radial tyres as they were with cross plys.

back in the cross ply days higher pressures would wear the middle, low the outer edges.
Radials are far better at keeping their correct shape, so you'd need to be running ridiculously high or low pressure to start having concerns about odd wear.


As for pressure, Mazda did indeed research the pressures etc, but they make those decisions based on a number of factors to make the majority of buyers happy.
So it's a compromise of comfort, grip, feel, etc.

Much the same as the seating position of the MX5, it's a compromise. If they set the seat lower to allow taller drivers to be completely comfortable shorter buyers wouldnt be able to see over the wheel, if they set the seat higher to make them fully comfortable taller drivers simply wouldnt fit.
So the seat is set at a midpoint where short drivers can make do, and tall drivers can make do.



At the end of the day, if the Mazda designed spec works for you, leave it and enjoy it. You're one of the lucky few that sits in the grey middle zone where it all works.
If you're in the outer zones where something isn't feeling right, change it.