Tyre Pressure?

[AnGeLiCdEmOn108]

i used to have

Tyre Brand: Falken Azenis ST115

Tyre Size: 205 55

Width of Rims: 7.5 J

Tyre Pressure (front): 32 psi

Tyre Pressure (back): 32 psi

 

[AnGeLiCdEmOn108]

now not sure, the tyre shop guy asked me to pump 34 or 36 psi but he was not sure and i think it is about time for me to pump again. guidance needed... searched the web but not much info on the measurement as the tyre and rims are no longer ori.

Tyre Brand: Dunlop DZ101

Tyre Size: 225 40

Width of Rims: 8 J (front) 9 J (back)

Tyre Pressure: Not sure

 

[AnGeLiCdEmOn108]

any suggestion mate?

 

[Mouse]

follow the recommended tyre pressure on your side driver door (a sticker), u wont go wrong with that. also the correct reading is always on cold tyre. if u pump 240kpa, notice the next morning before driving your tyre pressure will be 220, then after driving it u measure again it will back to 240 because of heat and pressure build up inside the tyre.

 

[bal3056]

If you put 26psi or 36psi but the recommended pressure is 32psi, then there is a cause for worry due to under or over-inflation. Don't worry too much and lose good sleep over whether it should be 31psi or 33psi from the recommended 32psi. There is always a + or - in any given situation.

Personally with the kind of rural and urban s**t roads we have these days, I usually stick to 30psi ... a good combo for comfort and performance, have been doing it all my life. Long hauls, I'll increase it to 32psi max.

Important thing is pressure should always be checked when tyres are cool ... I usually do it early mornings (same with engine oil level and belt tensioning).

 

[AnGeLiCdEmOn108]

follow the recommended tyre pressure on your side driver door (a sticker), u wont go wrong with that. also the correct reading is always on cold tyre. if u pump 240kpa, notice the next morning before driving your tyre pressure will be 220, then after driving it u measure again it will back to 240 because of heat and pressure build up inside the tyre.

agree with you Mouse. but the sticker on the driver's side door indicates tyre pressure for standard rims and tyre isn't it?

 

[AnGeLiCdEmOn108]

If you put 26psi or 36psi but the recommended pressure is 32psi, then there is a cause for worry due to under or over-inflation. Don't worry too much and lose good sleep over whether it should be 31psi or 33psi from the recommended 32psi. There is always a + or - in any given situation.

Personally with the kind of rural and urban s**t roads we have these days, I usually stick to 30psi ... a good combo for comfort and performance, have been doing it all my life. Long hauls, I'll increase it to 32psi max.

Important thing is pressure should always be checked when tyres are cool ... I usually do it early mornings (same with engine oil level and belt tensioning).

thanks for the advice mate. i am just wondering if the tyre pressure differs when the size of the rims and tyres is changed from standard specs. any comments?

 

[okow]

AnGeLiCdEmOn108...wah, susah la to type your nick.

Anyway, This is the pressure set up i'm on:

225/45/17 - 30 - 32psi

245/40/17 - 32 - 34psi

 

[c-square]

Guys, can I just ask a silly question.... why is it that the pressure at rear tyres are always higher compared to those at front, considering the fact that most of the time we do not have passangers at the backseat. The engine is at the front so presumably there is more load at the front most of the time, thus shouldn't it warrant a higher pressure?

 

[AnGeLiCdEmOn108]

AnGeLiCdEmOn108...wah, susah la to type your nick.

Anyway, This is the pressure set up i'm on:

225/45/17 - 30 - 32psi

245/40/17 - 32 - 34psi

hahaha sorry lah long nick like the animes... angeld will do. anyways, thank you for your tyre pressure info. mmm does that mean mine should be similar to yours or higher? only different is rims size and back tyre mine is thinner than yours.

at the moment my setup is 33 psi front and 35 psi rear. not sure whether if it is good.

 

[AnGeLiCdEmOn108]

Guys, can I just ask a silly question.... why is it that the pressure at rear tyres are always higher compared to those at front, considering the fact that most of the time we do not have passangers at the backseat. The engine is at the front so presumably there is more load at the front most of the time, thus shouldn't it warrant a higher pressure?

hi mate, a question is always not a silly question. normally the rear is pumped with greater pressure because;

1. BMW's are rear wheel drive.
2. Normally rear tyres are larger than the front.

however saying that even with the same tyre for all 4, it is still advisable to have greater pressure on the rear compared to front...

anyone with better explanation?

 

[metalrizca]

okeh..
just my guess..

maybe because the weight of the engine..
if you put more pressure to front tyres,
then, then handling will be too "ringan"..
so, its dangerous..

my 2 cents..

 

[3er]

To increase understeer for the average joe who doesnt know how to handle a RWD setup in an emergency or at the limits.

 

[AnGeLiCdEmOn108]

hahaha average joe... good one bro... mmm handling RWD is not as easy as handling the FWD... used to be able to handle FWD but RWD ???

 

[3er]

At the limits or in an emergency, dude. Sure, anyone can drive to Tesco and back - but what do you do when you lose the rear at a round about unexpectedly on a rainy night? More pressure at the rear lessens (not eliminates) this risk. Safer for the average joe....

 

[c-square]

At the limits or in an emergency, dude. Sure, anyone can drive to Tesco and back - but what do you do when you lose the rear at a round about unexpectedly on a rainy night? More pressure at the rear lessens (not eliminates) this risk. Safer for the average joe....

Now, I am more confused Why is it that more pressure at the rear lessens the risk of losing your rear? I thought by having lesser pressure there is a relatively bigger patch of the tyre sitting on the road, thus more traction (no?) compared with an high pressured tyre (slightly over-inflated ones)

 

[chubby]

stick to between 30 - 32 psi...that should do the job

 

[Mouse]

agree with you Mouse. but the sticker on the driver's side door indicates tyre pressure for standard rims and tyre isn't it?

i am not sure, but i think as long as your tyre size is correctly stated in the sticker, just follow the recommended pressure, not sure if the type and weight of rim have any effect on the recommended tyre pressure.

 

[3er]

Now, I am more confused Why is it that more pressure at the rear lessens the risk of losing your rear? I thought by having lesser pressure there is a relatively bigger patch of the tyre sitting on the road, thus more traction (no?) compared with an high pressured tyre (slightly over-inflated ones)

Lesser pressure doesnt always mean bigger contact patch. During emergencies, what do you usually do? You hit the brakes hard. So all the momentum goes to the tyres and in particular the sidewalls. So what happens in a soft, squishy underinflated tyres? It caves in in the middle of the contact patch. (Its a bit hard to describe without a picture or diagram) Thats why you usually see skid marks having two dark lines per wheel or side - just before it ends at the armco.

Higher pressure provides for more tyre stability from deformation so comparatively, you get a better, firmer, more even contact patch (therefore better grip) when you hit the brakes or at the limits. Only offset is that you have a slightly more bumpy ride on KL roads. (Oh yeah, you reduce the risk of a blowout or wheel damage if you have more pressure when you hit a bad pothole - something we all face in a 3rd world country...)

Hope that explains. If not, im sure someone else who can explain well will jump in.

 

[scin]

PARAMETER----TO INCREASE UNDERSTEER----TO INCREASE OVERSTEER
Front Tire Pressure-----Lower----------------------Higher
Rear Tire Pressure-----Higher----------------------Lower
Front Tire Width-------Smaller---------------------Larger
Rear Tire Width--------Larger----------------------Smaller