Your Tyre Pressure

[sirdistik]

I was just checking my tyre pressure tonight and noticed that both rear tyres were 27 PSI and 29 PSI for the front. i only just had it serviced too. is this something that Honda prefers? On the info sticker in the door it states 32 PSI for all tyres. everything is stock inc. 16" bridgestone tyres.

[JOhnnyFD]

32psi is the optimal tyre pressure for the stock tyres

[sirdistik]

That's what i thought. Steering is definately softer now. how often do you guys check your tyre pressure? the RAC recommends every week or 2..

[sKy.xD]

I hadn't checked mine for a year and when i did two weeks ago, it was still at the right tyre pressure...

[DLO01]

Theres no such thing as optimal. Theres pros and cons. And what you perfer/need. I have always used 34F 32R on my cars.

[dc2dc2dc2]

all comes down to what u like

[FDBenni]

34 F 33 R. soft sidewall :thumbdwn:

[JOhnnyFD]

That's what i thought. Steering is definately softer now. how often do you guys check your tyre pressure? the RAC recommends every week or 2..

2 or 3 weeks


I hadn't checked mine for a year and when i did two weeks ago, it was still at the right tyre pressure...

thats impossible.. how does that happen.. ur bound to lose tyre pressure definitely over a years time

[DLO01]

Semi Slicks. I don't think so.

[d@vid]

I am not sure about mine......

I think its 30psi for mine

[sirdistik]

Can anyone confirm whether you can get better grip with higher pressure? or maybe less?!? it'll probably have pros and cons to the life of the rubber i'm assuming.
i guess there's no one right answer but at the moment with my current setup (all stock) all i want is optimum grip and possibly max. life

[teaseR]

38F
36R
i drive on highways

[ekdez]

i put mine on 35 F and 33 R
depends on the tire tho..
ive put my stockies on 38 LOL and my dad uses 42psi :|

[J-MAN]

I have an FD, & when i am going around 100kms/hr I feel the car is somewhat veering slightly to the left. Not sure if it's just me or if the road is uneven or whatever.

do you guys think it has something to do with tyre pressure? i've got both front tyres at 30PSi.

Im thinking if i make the left front at 28 and keep the right at 30 that would somehow avoid the car veering to the left.

thanks.

[ekdez]

get a wheel allignment =]

[e240]

38psi hot all round...and that address the understeer on the R888...LOL

[sirdistik]

My FD2 pulls to the left too. you can't drive and take your hands off for too long, otherwise it'll run off road. it just won't drive straight.

I read somewhere that this is supposed to be normal (can't remember where i read it) and Honda's response was "it's better than it pulling to the right into oncoming traffic" .. something like that.

[OMG.JAI xD]

25psi in the front and 32 in the rear.

Too much camber. I lower my pressures so the tyre sits more flat on the road. Having more contact.
You dont get a very nice fuel efficiency. But understeer is minimised, less wheelspin in the rain during take off at a very steep hill.

[OMG.JAI xD]

My FD2 pulls to the left too. you can't drive and take your hands off for too long, otherwise it'll run off road. it just won't drive straight.

I read somewhere that this is supposed to be normal (can't remember where i read it) and Honda's response was "it's better than it pulling to the right into oncoming traffic" .. something like that.

When you say a car pulls it means when the steering wheel is straight the vehicle veers to one side.
If you take your hands off the steering wheel and the vehicle veers, thats called wandering.
Both is an alignment issue.
But wandering can be cause by the surface of the road.
The design of the roads on a country that is left hand drive is so that the water flows towards the kerb (which is left). So the road is never 100 percent straight or flat.
It will have a slight incline or decline going horizontally on the road.

And really. You shouldnt be letting your hands off the wheels at anytime.

[d@vid]

Same here, my car seems to learn towards the left as well.

Could it be tyre pressures

[mickyh]

My FD2 pulls to the left too. you can't drive and take your hands off for too long, otherwise it'll run off road. it just won't drive straight.

I read somewhere that this is supposed to be normal (can't remember where i read it) and Honda's response was "it's better than it pulling to the right into oncoming traffic" .. something like that.

:thumbsup: I seem to remember that by regulations the wheel alignment must be slightly biased to the left, for safety reasons.

[sirdistik]

it actually pulls quite a bit.. on a straight road (even when i'm travelling right on the median strip between two lanes, no traffic) it pulls to the left.. i'm constantly having to pull it to the right to drive straight, and it's bloody tiring.

i'll take it in to get the wheels aligned when i get time

[Toilet]

38psi all round too, steering seems more responsive compared to when I had 34 all round.
Plus my sidewall doesn't bulge as much.

[FallenAngel]

38F 36R

Keep in mind ALL ROADS (esp with highway driving), the road is designed to have a slight camber about 0.5 - 1deg, for safety reasons. Just say if you fell asleep at the wheel, the car would veer left because of it to avoid a head of collision or stuff like that.

Wheel alignment is usually the other thing to check.

[DLO01]

And drainage???

[FallenAngel]

That too.. =]

[JOhnnyFD]

i'm on 42F & R lmao.. my yoko's max is 44

didnt pump up my tyres for a month and it was on 38

[MMike]

I run; front 35PSI / rear 32PSI for everyday driving.

[sirdistik]

Damnnnn!! Everyone's PSIs are pretty high.. Do most of you guys pump more cos it's more fuel efficient? Or do you get better grip? cos i would have thought that the recommended 32PSI would be optimal? Hrmm.. maybe i should pump more in?

[JOhnnyFD]

different tyres have different recommended PSI

stock tyres are 32psi.. recommended PSI gives better fuel efficiency, better road grip... u dont want too soft of a tyres (easy punctures, less fuel efficiency) or over inflate (stretching the rubber and would give less road contact), and it makes the tyres last longer

[curtis265]

I use 36 - At a drive safe course they told me that manufacturers tell u to use 32 in order to optimise noise and traction and therfore safety. 36 is for maximum traction, but not as great comfort.

edit: this is for my 16x6.5 inch wheels running 205/55/R16 tyres

[OMG.JAI xD]

I use 36 - At a drive safe course they told me that manufacturers tell u to use 32 in order to optimise noise and traction and therfore safety. 36 is for maximum traction, but not as great comfort.

edit: this is for my 16x6.5 inch wheels running 205/55/R16 tyres

You actually get less traction with high pressures.

Higher pressures doesnt mean the tyre sits on the road with more force.
It basically raises the tyre.
You have less contact with higher pressures.

And my proof of this, is. When you have a 4wd or atv on sand. You dont pump your tyres to max pressure. It will just dig down into the sand.
You run low pressures, so you have more contact width, hence more traction.

Its not very safe pumping tyres to that high, unless stated by manufacturer.
Put into consideration that the air we pump into the tyres arent 100% oxygen.
And that air mixture in the tyre heats up. Anything that is heated expands.
If you have 36psi cold. Youll end up with at least 38-40 psi at Normal Operating Temperature.
Last thing you want is your tyres popping when youre on the highway overtaking somone at 110kmh+.

[curtis265]

You actually get less traction with high pressures.

Higher pressures doesnt mean the tyre sits on the road with more force.
It basically raises the tyre.
You have less contact with higher pressures.

And my proof of this, is. When you have a 4wd or atv on sand. You dont pump your tyres to max pressure. It will just dig down into the sand.
You run low pressures, so you have more contact width, hence more traction.

Its not very safe pumping tyres to that high, unless stated by manufacturer.
Put into consideration that the air we pump into the tyres arent 100% oxygen.
And that air mixture in the tyre heats up. Anything that is heated expands.
If you have 36psi cold. Youll end up with at least 38-40 psi at Normal Operating Temperature.
Last thing you want is your tyres popping when youre on the highway overtaking somone at 110kmh+.

A lower pressure makes the cross section of the tyre 'w' shaped, whereas the 36 makes it a squarish U shape... supposively.

I need to try this myself i guess.

your tyre will not ever pop at 40 psi (heated)

[FallenAngel]

A lower pressure makes the cross section of the tyre 'w' shaped, whereas the 36 makes it a squarish U shape... supposively.

I need to try this myself i guess.

your tyre will not ever pop at 40 psi (heated)

Sorry have to go against taht lol. Had my stocks on 40 hot with 5 people in the car on a road trip and the rear left popped.

[sirdistik]

lol.. probably cos you had 5 ppl in it. i guess having 5 ppl in the car would put more pressure on the tyres itself, so it'd be >40PSI .. we'll that's my logic.. correct me if i'm wrong

[JOhnnyFD]

5 ppl.. tats heavy

too high of a pressure with alot of weight.. bust.. and more so going at speed as it puts on more pressure onto the tyres (as ppl should know heat expands the air)

[FallenAngel]

lol.. probably cos you had 5 ppl in it. i guess having 5 ppl in the car would put more pressure on the tyres itself, so it'd be >40PSI .. we'll that's my logic.. correct me if i'm wrong

Yes although technically he said 40psi heated he did mention weight. English is a bitch and can be argued but anyways its not a big fuss -_-

[fitvpower]

hmm if you get camber wear and cant afford camber kits..is it aiight just to lower the tyre pressure

[DLO01]

It helps to a degree, but definatly won't solve the problem.

[curtis265]

Sorry have to go against taht lol. Had my stocks on 40 hot with 5 people in the car on a road trip and the rear left popped.

how old were your tyres? were they slightly damaged? of course, any sort of scratch or something with a thinning effect will weaken the tyre significantly

[fitvpower]

i get bad ass camber wear...when i get a wheel alignment if i ask to put it on stock setting that will that take away camber wear?

soz for the noobness..

[OMG.JAI xD]

A lower pressure makes the cross section of the tyre 'w' shaped, whereas the 36 makes it a squarish U shape... supposively.

I need to try this myself i guess.

your tyre will not ever pop at 40 psi (heated)

Put into consideration every car is placed with negative camber.
A "U" shaped tire will have more contact on which ever side is being leaned towards the camber.

With a "W" type. You have room for wheel contact point as the wheel turns.

And a "W" cross section is only valid to a certain degree where youre under inflating the tyre.

Also put into consideration of centrifugal force.
If a wheel is spinning. The air pressure in the tyre will be diverted away from the rim or in other words, more biased towards the tread of the wheel.
Eventually. Going on a fast enough speed (60kmh lets say) that W turns into a U cross section with a better width contact.
You inflate a tyre with a high pressure, that U cross section will only get sharper.

If you want to test which is better.
Go on a wet track. Test with 40 psi and test with 20 psi.
Test it with the same car. In this case. A front wheel drive. And evaluate at what speeds the car understeers and how fast it can recover.

[DLO01]

i get bad ass camber wear...when i get a wheel alignment if i ask to put it on stock setting that will that take away camber wear?

soz for the noobness..

Nope. +ve Toe will help with camber wear, which is not a stock setting.

Any decent wheel aligner can tell you if they can adjust out your camber wear and adjust it to suit. Otherwise they will tell you you need a camber kit.

[FallenAngel]

how old were your tyres? were they slightly damaged? of course, any sort of scratch or something with a thinning effect will weaken the tyre significantly

10000kms approx.

It just literally split to the thread.

[curtis265]

hmmmmm I see what yo're saying, omgJAIxD

I never thought of that to argue with the guy when i was there lol...

[OMG.JAI xD]

hmmmmm I see what yo're saying, omgJAIxD

I never thought of that to argue with the guy when i was there lol...

Lol yeh well it takes abit of thinking.

What people have been taught is from the old days where the profile of the tyre is as high as 60-70.
Now we have wider wheels. bigger diameters. Lower profiles.

Same basics apply. But the standards are changed.


=]
High pressures is good for fuel efficiency though.

[curtis265]

then wut about bikes who take like.. 50 PSI and have about 1cm of tyre touching the road...

the stress on the ground from the tyre is a lot greater because the weight is concentrated into a smaller area... does that mean more or less traction for the vehicle? That confuses me because i've heard things about hwo small car putting like.. wheels too wide, and then they become less grippy...

and then with camber, the surface area of contact with the road is also decreased too (good for cornering but straight-line accelration has more or less traction??)

Did u get what i'm saying :S that's just everything blurted out in one go... (apologies)

[FallenAngel]

then wut about bikes who take like.. 50 PSI and have about 1cm of tyre touching the road...

the stress on the ground from the tyre is a lot greater because the weight is concentrated into a smaller area... does that mean more or less traction for the vehicle? That confuses me because i've heard things about hwo small car putting like.. wheels too wide, and then they become less grippy...

and then with camber, the surface area of contact with the road is also decreased too (good for cornering but straight-line accelration has more or less traction??)

Did u get what i'm saying :S that's just everything blurted out in one go... (apologies)

Ok first obvious point is that bikes are lighter than cars.
Basically weight plays a major factor when it comes to traction. The more weight the object has the more "grip" it requires to hold it. Even though more force is exerted to the ground, when cornering the downward force will change its direction according to the turn (not sure if you get what i mean there).
Just say a car takes a corner at its limit before any traction loss occurs is @ 50km/h, a bike could probably take it at 80km/h using the same amount of traction required by the car.
[There is a formula in physics that will tell u this but i can't remember it]

Also the more surface area the better, such as the more "tyre" on the ground is better. Although weight will also determine how much force will be put down. The more force in the same surface area, the more traction you will get. Just say like bike weighs 100kg (i actually dont know the real weight) and the surface area of the 2 tires touching the ground is 1m squared. A ratio can be thought of 100:1
On a car, the weight could be say 1000kg but the surface area by 4 tyres is 10m squared, so the ratio is the same 1000:10 -> 100:1
This means the traction is the same across both objects.
(Just trying to get the point across, these figures are probably wrong haha)

Wide tyres usually give more grip as it gives more surface area of the tyre touching the ground. (USUALLY not all the time)

Camber will increase cornering traction as the tyre wall will flex according to the corner. Just say u take a left turn, the tirewall will flex towards the right, and if the tyres have camber then it will conteract this flex and align the tyre to be as if it had no camber on the straight for the duration of the turn.

[ ] -> \ \
----- ------- (the road should angle up abit like / )

Not sure if you can understand this but i tried lol.

I might fix up this post later

[OMG.JAI xD]

To put it simply.

A bike needs to be leaned to turn instead of turning the wheels.

The design of a bike tyre is more pointed because it needs to maintain the same amount of surface area contact during cornering and the straights.

A car has 2 wheels in the front that changes its contact point while its turning. Or 4 if it has 4 wheel steering.

The engineering on those 2 vehicles are completely different.

[curtis265]

Ok first obvious point is that bikes are lighter than cars.
Basically weight plays a major factor when it comes to traction. The more weight the object has the more "grip" it requires to hold it. Even though more force is exerted to the ground, when cornering the downward force will change its direction according to the turn (not sure if you get what i mean there).
Just say a car takes a corner at its limit before any traction loss occurs is @ 50km/h, a bike could probably take it at 80km/h using the same amount of traction required by the car.
[There is a formula in physics that will tell u this but i can't remember it]

Also the more surface area the better, such as the more "tyre" on the ground is better. Although weight will also determine how much force will be put down. The more force in the same surface area, the more traction you will get. Just say like bike weighs 100kg (i actually dont know the real weight) and the surface area of the 2 tires touching the ground is 1m squared. A ratio can be thought of 100:1
On a car, the weight could be say 1000kg but the surface area by 4 tyres is 10m squared, so the ratio is the same 1000:10 -> 100:1
This means the traction is the same across both objects.
(Just trying to get the point across, these figures are probably wrong haha)

Wide tyres usually give more grip as it gives more surface area of the tyre touching the ground. (USUALLY not all the time)

Camber will increase cornering traction as the tyre wall will flex according to the corner. Just say u take a left turn, the tirewall will flex towards the right, and if the tyres have camber then it will conteract this flex and align the tyre to be as if it had no camber on the straight for the duration of the turn.

[ ] -> \ \
----- ------- (the road should angle up abit like / )

Not sure if you can understand this but i tried lol.

I might fix up this post later


To put it simply.

A bike needs to be leaned to turn instead of turning the wheels.

The design of a bike tyre is more pointed because it needs to maintain the same amount of surface area contact during cornering and the straights.

A car has 2 wheels in the front that changes its contact point while its turning. Or 4 if it has 4 wheel steering.

The engineering on those 2 vehicles are completely different.

Ok let's not take cornering into account then to make this a bit more simple - straight line only.

Traction is the ratio between the forces exerterd by a vehicle through the wheel, and the weight supported by the wheel. - forces in two directions which have no effect on each other. A 1000 kg car would be able to put down 10 times the force to the ground than a 100 kg cyclist - as Fallenangel said.

I do too believe that a fatter wheel would increase the traction... but the pressure applied to the ground would be less because the weight would be more spread out. This would mean that the car can exert less force to the ground...

The above paragraph makes sense to me, but i can't accpet how a fatter tyre would be less forceful, and have never figured out how to disprove what i just said... Someone do so! and save me before i go insane..

[FallenAngel]

Haha i tried... someone else have a go xD

[OMG.JAI xD]

Ok let's not take cornering into account then to make this a bit more simple - straight line only.

Traction is the ratio between the forces exerterd by a vehicle through the wheel, and the weight supported by the wheel. - forces in two directions which have no effect on each other. A 1000 kg car would be able to put down 10 times the force to the ground than a 100 kg cyclist - as Fallenangel said.

I do too believe that a fatter wheel would increase the traction... but the pressure applied to the ground would be less because the weight would be more spread out. This would mean that the car can exert less force to the ground...

The above paragraph makes sense to me, but i can't accpet how a fatter tyre would be less forceful, and have never figured out how to disprove what i just said... Someone do so! and save me before i go insane..


With a high pressure tyre. (more pointed). There would be less road contact.
But the force is greater.
You lower the pressure you have less force but more contact.
And it also depends on the drive type.
A rear wheel drive will have alot more force applied to the wheels during take off or launch, and a front wheel drive will have less force applied to the driving wheels, as a vehicles tends to lift off during take off, exerting all the force towards the rear.

Ever tried doing a burnout in a front wheel drive?
High pressures will bunny hop.
Lower pressures will let it spin.

Its very hard to get into detail. But lets say you have 35psi with 5" effective road contact with 200kg on each front wheel. 5x200x35 = 35000 units.
Compared to 25psi with 8" effective contact. 8x200x25 = 40000 units. Even with 7" effective road contact, it equals up to 35000.

That is not a formula. But its something i made up to prove my point.
With 35 psi of contact on 5" effectively on the road. You have 35psi @ 200kg on that area.

While having 25psi @ 200kg with 7 or 8" effective area contact, You still have the same amount of forces but its more spread out.

Its hard to explain. But put into consideration. That tyre pressures vary with different conditions.
and what I wanted the point i wanted to bring across is that if you can have the same amount of traction at 35psi and 25 psi. Wouldnt it be better to be at 25psi to leave for changes in temperature, surfaces, load etc etc?

Force applied to the ground is not all based on tyre pressures.

My head hurts.