Go Back   Team-BHP > Under the Hood > Technical Stuff


Reply
 
Thread Tools Search this Thread
Old 30th January 2009, 21:11   #61
Senior - BHPian
 
quickdraw's Avatar
 
Join Date: Mar 2008
Location: New Delhi
Posts: 1,008
Thanked: 1,282 Times
Default

Is there any proper way to calculate PSI for non OEM tires and rims? Case being my car I keep it at 32 the gentleman I bought it from recommends it to keep the rims from getting damaged.
quickdraw is offline   Reply With Quote
Old 18th March 2009, 19:56   #62
BHPian
 
djavalkar's Avatar
 
Join Date: Dec 2005
Location: Pune
Posts: 42
Thanked: 8 Times
Default 195/60R15 Bridgestone Potenza Tyre pressure

Hi,
I wanted to know what is the preferred tyre pressure for the 195/60R15 Bridgestone Potenza Tyre pressure for City and Highway Drive.
I tried keepng thr tyre pressure at 33 psi but I am seeing uneven wear on the tyre ..there is a difference of about 1 mm between the threads ( along the same line). So before the damage is done I would like to keep the tyre pressures at normal level.
Note : Most of my driving is in the city.

Regards
Dhananjay

Note from Team-BHP Support : Thread MERGED. Please use the search feature before creating a new thread on a topic that might already exist. Please continue your discussion in an existing thread. This will keep all the relevant information in one place and make it easier for readers in the future.

Last edited by Jaggu : 18th March 2009 at 21:02. Reason: Search please
djavalkar is offline   Reply With Quote
Old 19th March 2009, 09:48   #63
BANNED
 
Join Date: Jan 2009
Location: Bangalore
Posts: 135
Thanked: 38 Times
Default

I have provided some inputs in this area that might be helpful. Please see my post at http://www.team-bhp.com/forum/test-d...automatic.html (Another automatic in the house - i10 Automatic).

Regards,
Sandeep Menon
sdmn is offline   Reply With Quote
Old 19th March 2009, 11:12   #64
BHPian
 
UniqueMods's Avatar
 
Join Date: Nov 2008
Location: Mumbai
Posts: 308
Thanked: 49 Times
Default

the recommended psi for 175/185/195 60 R15 is 30.
with this pressure the tire wear will be even and not focused on the center in case of 33/34 psi.

with the tire of 60hight rubber, the rims/ alloys can be dented in highway sudden potholes, but withing the city 30psi is sufficient to save the rims and also the tires.

um
UniqueMods is offline   Reply With Quote
Old 19th March 2009, 12:08   #65
BANNED
 
Join Date: Jan 2009
Location: Bangalore
Posts: 135
Thanked: 38 Times
Default

Quote:
Originally Posted by suman View Post
Anyone used a Digital Tyre Pressure gauge (hand held) lately? Any idea how accurate or reliable they are? Or are the old fashioned analogue ones better?
I use an Accutire digital pressure gauge for my cars. Bought it in the US (From Costco) and brought it with me to India. Very accurate. Now I know which petrol pumps in my area have an accurate air pump. For some pumps where I regularly visit but whose pumps have wrongly calibrated gauges, I know the zero error. For example there is one enroute home from office, where I ask for 37 with a warm tire, and I know I'm getting 33 cold. I double check it the next day at cool air temperatures using my digital gauge, and confirm that it is indeed 33.
sdmn is offline   Reply With Quote
Old 19th March 2009, 12:53   #66
BHPian
 
UniqueMods's Avatar
 
Join Date: Nov 2008
Location: Mumbai
Posts: 308
Thanked: 49 Times
Default

i never knew there would be such a huge difference in the cold and warm tire psi.

So when the car companies recommend 32 front and 30 rear, do they mean cold or warm psi ?

Anyways while driving and what really matters - tires will be warm, so the psi should be around 32 front and 30 rear (for Santro).

By the time one drives to a pump, the tires would be warm and get the correct driving psi required. after parking overnight the tries may look low.

UM

Last edited by UniqueMods : 19th March 2009 at 12:57.
UniqueMods is offline   Reply With Quote
Old 19th March 2009, 14:08   #67
BANNED
 
Join Date: Jan 2009
Location: Bangalore
Posts: 135
Thanked: 38 Times
Default

I think I did not word that accurately. What I meant was that, the pump has an error of about 3PSI, and the temperature perhaps causes another 0.5 or 1 PSI difference.

Speaking about cold and warm air pressures, all manufacturer recommended tire pressures are cold. Hyundai defines that as 1.6km or 1 mile driving distance. So the manual says that you must check pressure when you have driven less than 1.6km.

Also, after a 10 to 20 km drive in the city (not long drives on the highways), feel your front and rear tires with the back of your hands. You will notice that the front tires are warmer due to the engine heat, and the rear tires are cooler. This too will make a difference if you check air after driving such distances.

If you have your own gauge, then top up a little excess air at the pump and correct the pressure during early mornings before driving. This is what I do. In case you don't have your own gauge, then drive less than 1.6KM to a pump, and then check air pressure. Of course, this is not going to make a huge difference, and matters only if you are a perfectionist. (I certainly have that weakness).

Also, more significant than the temperature is to make sure your petrol pump digital gauge is accurate. Many digital gauges at our petrol pumps are wrongly calibrated. I have found differences up to 5 PSI between pumps.
sdmn is offline   Reply With Quote
Old 19th March 2009, 14:18   #68
Senior - BHPian
 
Join Date: Sep 2007
Location: New Delhi
Posts: 3,083
Thanked: 252 Times
Default

Quote:
Originally Posted by sdmn View Post
Also, after a 10 to 20 km drive in the city (not long drives on the highways), feel your front and rear tires with the back of your hands. You will notice that the front tires are warmer due to the engine heat, and the rear tires are cooler. This too will make a difference if you check air after driving such distances.
Sorry, I think you've got it wrong.
It's not because of engine heat but because the front wheels do MOST of the braking, discs in modern cars!
anupmathur is offline   Reply With Quote
Old 19th March 2009, 14:51   #69
BANNED
 
Join Date: Jan 2009
Location: Bangalore
Posts: 135
Thanked: 38 Times
Default

Quote:
Originally Posted by anupmathur View Post
Sorry, I think you've got it wrong.
It's not because of engine heat but because the front wheels do MOST of the braking, discs in modern cars!
Are you sure? My Verna has all 4 discs (since it has ABS) and why do you think front brakes generate so much more heat than the rear so much so that one can feel it on the tires? Because the weight of the car is thrown onto the front brakes? I find that difficult to believe. Cannot think of any other reason than engine heat.
sdmn is offline   Reply With Quote
Old 19th March 2009, 15:05   #70
Team-BHP Support
 
Jaggu's Avatar
 
Join Date: May 2004
Location: Bangalore
Posts: 17,742
Thanked: 7,449 Times
Default

Quote:
Originally Posted by sdmn View Post
Are you sure? My Verna has all 4 discs (since it has ABS) and why do you think front brakes generate so much more heat than the rear so much so that one can feel it on the tires? Because the weight of the car is thrown onto the front brakes? I find that difficult to believe. Cannot think of any other reason than engine heat.
Weight transfer to front will put more stress on front tires & brakes, hence the front disc's are bigger compared to rear's. Engine heat will have minimal effect on tire temp since the car is moving and cool air keeps the hear away, also the firewall/engine bay does a pretty good job at insulation
Jaggu is online now   Reply With Quote
Old 19th March 2009, 15:06   #71
Senior - BHPian
 
Join Date: Sep 2007
Location: New Delhi
Posts: 3,083
Thanked: 252 Times
Default

Quote:
Originally Posted by sdmn View Post
Because the weight of the car is thrown onto the front brakes?
See! You knew it all along! This has to do with the laws of Physics, not so much with ABS and EBD! The front brakes ALWAYS have to do more work. Assuming, of course that you travel AHEAD most of the time, LOL!
anupmathur is offline   Reply With Quote
Old 19th March 2009, 15:13   #72
Senior - BHPian
 
Raccoon's Avatar
 
Join Date: Jan 2008
Location: Poona
Posts: 1,832
Thanked: 105 Times
Default

^^^Ditto in my Esteem. The front tyres are always hotter. And I'm pretty sure this isn't just because of the front discs. The rims feel even hotter... and I'm sure they transfer heat to the tyres.

This heating happens even on rides where the brakes are seldom used!
Raccoon is offline   Reply With Quote
Old 19th March 2009, 15:17   #73
BANNED
 
Join Date: Jan 2009
Location: Bangalore
Posts: 135
Thanked: 38 Times
Default

Interesting...but tell me...is the difference so much that during the short durations of braking, the temperature difference is so much that you feel the heat in the front tires and do not feel it in the rear tires? Sure that's not engine heat? Remember, I'm asking about 10 to 20 kms in the city, when air flow is not great under the car.
sdmn is offline   Reply With Quote
Old 19th March 2009, 15:21   #74
Team-BHP Support
 
Jaggu's Avatar
 
Join Date: May 2004
Location: Bangalore
Posts: 17,742
Thanked: 7,449 Times
Default

Quote:
Originally Posted by sdmn View Post
Interesting...but tell me...is the difference so much that during the short durations of braking, the temperature difference is so much that you feel the heat in the front tires and do not feel it in the rear tires? Sure that's not engine heat? Remember, I'm asking about 10 to 20 kms in the city, when air flow is not great under the car.
Yup take a 2 wheeler (engine is far away from brakes) and replicate, if you want in neutral, front will become hot compared to warm at rear.

I would give some 5 to 10 % more for engine bay heating the front brakes in a car, my own guess estimate no scientific instrument involved in this

EDIT: 5% is max dont think even 10% is possible
Jaggu is online now   Reply With Quote
Old 19th March 2009, 16:00   #75
BANNED
 
Join Date: Jan 2009
Location: Bangalore
Posts: 135
Thanked: 38 Times
Default

Pointers to any credible web site will of great help to understand. In a quick Googling attempt, I could not find anything.
sdmn is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
"Cayenne" we "XC-eed" in our "Endeavour" to "Safari"? Taking powerful metal off-road SS-Traveller 4x4 Excursions 55 10th November 2016 22:56
Problem in filling petrol with "Auto Cutoff" feature RajeshK Technical Stuff 48 26th September 2014 13:49
Mantri Square at Malleshwaram...a traffic nightmare? n_mouli Street Experiences 45 27th March 2010 09:18
"Importing" Laptops to India - How many per person? Rehaan Gadgets, Computers & Software 23 10th February 2010 06:28
13 inch versus 12 inch wheels for the ZEN raghuram.cg Technical Stuff 5 30th March 2006 08:10


All times are GMT +5.5. The time now is 06:27.

Copyright 2000 - 2017, Team-BHP.com
Proudly powered by E2E Networks