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Old 10th January 2006, 17:56   #31
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Arrow Trip meter is optimistic on smaller tires

Quote:
Originally Posted by Ajay
The Tire upsize now has resulted in reduced FE. Stock tires- 175/80/R13, Upsized to 205/50/R15. On Shell super unleaded gives me about 9km/litre in B'lore traffic to 11km/ litre before the upsize.
I understand the resulting speedo error, but does the trip meter error out in case of a tire upsize? Is this normal for this kinda tire upgrade or is there someother culprit?Please help clarify.
I have heard people say that switching to alloys with wider tires usually result in a drop in fuel efficiency. I am not sure if thats because of the larger mass of the aftermarket tire (wider tires negate the effect of weight-saving alloys) or increased rolling resistance.

I certainly don't think its a reading error. Here's why.

Lets assume that your older tires rotated say, 100 times to cover 1km. Your trip meter shows 1km covered. What it actually knows is that your tires have rotated 100 times. Thats all.

Now considering that your newer tires have to rotate longer to cover the same distance (becuase you now have a smaller diameter and consequently lower tire circumference), we'll assume a figure of 120 revolutions to cover the same distance of 1km (120 is an exaggeration, but to explain a point).

However, your tripmeter does not know of a diameter change and only knows that your wheels have turned 120 times. So it will show that you have covered 1.2 kms while you have actually covered only 1km.

See what I am getting at? Your tripmeter is showing you a higher figure than what you have actually travelled.

So if it says 9km on it, it is in actual likely to be less than 9kms, not higher. I hate to be a person to break bad news, but in all likelihood, your fuel efficiency is worse than what it shows on your trip meter.

Hope this makes sense.

sAP
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Old 10th January 2006, 18:04   #32
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Quote:
Originally Posted by sAP
Hope this makes sense.
Or you could have just pointed him to this link. His speedo shows 4% more than actual, therefore he has to divide his actual reading by 1.04 before calculating FE.
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Old 10th January 2006, 18:53   #33
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Quote:
Originally Posted by sAP
I have heard people say that switching to alloys with wider tires usually result in a drop in fuel efficiency. I am not sure if thats because of the larger mass of the aftermarket tire (wider tires negate the effect of weight-saving alloys) or increased rolling resistance.

I certainly don't think its a reading error. Here's why.

Lets assume that your older tires rotated say, 100 times to cover 1km. Your trip meter shows 1km covered. What it actually knows is that your tires have rotated 100 times. Thats all.

Now considering that your newer tires have to rotate longer to cover the same distance (becuase you now have a smaller diameter and consequently lower tire circumference), we'll assume a figure of 120 revolutions to cover the same distance of 1km (120 is an exaggeration, but to explain a point).

However, your tripmeter does not know of a diameter change and only knows that your wheels have turned 120 times. So it will show that you have covered 1.2 kms while you have actually covered only 1km.

See what I am getting at? Your tripmeter is showing you a higher figure than what you have actually travelled.

So if it says 9km on it, it is in actual likely to be less than 9kms, not higher. I hate to be a person to break bad news, but in all likelihood, your fuel efficiency is worse than what it shows on your trip meter.

Hope this makes sense.

sAP
Will this kind of tire upgrade make this huge a difference in the FE? Might there be something else in addition to this? Got the timing checked, Tappet adjustments done but still the same.Thanks anyways Sap
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Old 11th January 2006, 18:19   #34
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I have upgraded to 14x6 league LG175, hyper silver alloys on my baleno... along with 185/65R14 goodyear eagle NCT5 tubeless tyres. Major alloy specs are exact matches to stock wheels (4 holes, 100 PCD, 38 offset) except for center bore. Took the car yesterday to NH7 for checking vibrations due to improper centering... ripped it till 120kmph... unfortunately, the steering did vibrate after 100kmph! A friend of mine sitting in the front passenger seat did not "feel" those vibrations, but could "see" the steering shaking... I could do both!!

Though it was so unpleasant experience with the new car, it still could not bother me much since I already knew its not so serious matter... especially due to the proven remedy to the problem (courtesy sAP!)

I had even tried spinning all wheels while they are lifted on jacks and observing any irregularities. Could see some minor "run-out", guess it was a couple of mm at the most. However, I did not argue with the tyre-wala further because he had done his best, so I didn't see any point there. None of the tyre/alloy/car dealers I met so far was aware of centering rings... surprising!

Moral of the story is I must get those custom-made rings now (along with another pinch to the pocket!). It would have been great to know some local source for the same in Bangalore (if somebody has any idea, please do post details. It will be quite useful for many). In the worst case, I think I will have to order it from the person in Chennai as mentioned by sAP!
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Old 12th January 2006, 10:44   #35
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Quote:
Originally Posted by santosh.s
I have upgraded to 14x6 league LG175, hyper silver alloys on my baleno... along with 185/65R14 goodyear eagle NCT5 tubeless tyres. Major alloy specs are exact matches to stock wheels (4 holes, 100 PCD, 38 offset) except for center bore. Took the car yesterday to NH7 for checking vibrations due to improper centering... ripped None of the tyre/alloy/car dealers I met so far was aware of centering rings... surprising!

Moral of the story is I must get those custom-made rings now (along with another pinch to the pocket!). It would have been great to know some local source for the same in Bangalore (if somebody has any idea, please do post details. It will be quite useful for many). In the worst case, I think I will have to order it from the person in Chennai as mentioned by sAP!
Feels bad aint it? I was aware of the tradeoff on reduced FE after upgrading but after looking at the FE now .Speak to the Pitstop guys next to Tyre tech near richmond circle , they will get it done.Preferably get Aluiminium rings for about Rs.250 each.
The main thing would be to ask the lathe guy to directly take measurments of the centre bore rather than just giving them the spare wheel. This way you can get exact fit rings made.Even better if you can get the Maruti service guys to make one for you.
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Old 12th January 2006, 13:36   #36
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yes, of course it feels bad! but this is one time effort, which should be fine... except for informing service guys about those rings every time you need to remove wheels and making sure rings are fitted back!

Since my tyre OD is very close to original (just +0.3%) and the width is not too large, I hope it won't reduce my FE significantly. In fact goodyear claims that NCT5's have less rolling resistance material ("eco" tyres), MUL uses exactly the same tyres/size for baleno-vxi and GM for optra, skoda for octavia (bigger size), and even some mercedece cars have it as default (though they may be using "made in germany" ones, as one guy told me!). I chose this tyre because I came across a few good reviews about it on tbhp (particularly remember +ve feedback by "buffetfan"), thought that this should be a decent all-rounder, if not ultra-high performer... which came cheap too (Rs. 4k under exchange for a set of 5)

@rings, will first contact the maruti dealer... if he doesn't help then will visit pitstop soon
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Old 20th January 2006, 00:53   #37
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My only suggestion would be to try and get the wheel balancing done again....I did have steering vibration after tyre exchange but I guess it was maybe tyre "bedding in" or something like that...I did another visit to the tyrewallah and he found a balancing mistake...after he corrected this..the vibrations were gone...
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Old 20th January 2006, 01:07   #38
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anyone know where one can get hub-centric rings in bangalore????
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Old 20th January 2006, 01:29   #39
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The actual FE does not change with tire upgrade until and unless there is drastic change in aerodymanics or weight etc. It is only apparent due to change in circumference of the tires.


I had once experienced this kind of problem with a high speed cutting disc. The fitter had replaced a disc with a larger bore dics than the original one and when he was using it, it was vibrating like hell. We had to machine a hub centering ring and fit it to get rid of vibrations.

RK
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Old 20th January 2006, 11:06   #40
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Quote:
Originally Posted by adit1329
anyone know where one can get hub-centric rings in bangalore????
You can try the PitStop next to tyretech ( near Richmond Circle).
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Old 20th January 2006, 11:14   #41
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Quote:
Originally Posted by adit1329
anyone know where one can get hub-centric rings in bangalore????
I checked with the maruti dealer, but they can't help it. I met a service manager who was quite co-operative, took me to the workshop to understand what exactly I need. But he said he can not get those rings made. However, he offered to lift the car and adjust run-outs if any, though! Since that wouldn't be a permanent solution, I didn't do that.

Then I visited "pitstop" guys as suggested by Ajay. He said he can make hub rings (asked for Rs 300 per ring for aluminium material, that adds to the cost of alloys which is already a costly affair, especially in bangalore!). I am waiting for my 5th alloy before putting rings. (one of the piece in the set was "showroom" piece with small chippings, which I had to reject and demand a new replacement)

One good thing was that the guy said he will firmly fix those rings to alloys, so that you need not worry about misplacing... don't know how. For directions- take the road below richmond circle flyover wing towards KH road (lalbag), pitstop is located at the next signal that you find under the bridge itself.
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Old 20th January 2006, 11:31   #42
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hi everyone,

my 2005 zen's steering wheel starts to vibrate at around 75-80 kph. do i need "the rings" or any other solution is available. what specifications do the rings need to be to solve this problem. also, are these rings available somewhere in south delhi.

tyre size is 175/60r14 ( as of now) but i'm going in for 185/45r14 this saturday or sunday max.

please help,

regards
anuj

Last edited by rev_hard : 20th January 2006 at 11:32.
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Old 20th January 2006, 11:52   #43
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Quote:
Originally Posted by santosh.s
I checked with the maruti dealer, but they can't help it. I met a service manager who was quite co-operative, took me to the workshop to understand what exactly I need. But he said he can not get those rings made. However, he offered to lift the car and adjust run-outs if any, though! Since that wouldn't be a permanent solution, I didn't do that.

Then I visited "pitstop" guys as suggested by Ajay. He said he can make hub rings (asked for Rs 300 per ring for aluminium material, that adds to the cost of alloys which is already a costly affair, especially in bangalore!). I am waiting for my 5th alloy before putting rings. (one of the piece in the set was "showroom" piece with small chippings, which I had to reject and demand a new replacement)

One good thing was that the guy said he will firmly fix those rings to alloys, so that you need not worry about misplacing... don't know how. For directions- take the road below richmond circle flyover wing towards KH road (lalbag), pitstop is located at the next signal that you find under the bridge itself.
Santosh, Ask this guy to take the exact measurement of the Center bore. They usually take just your spare wheel and make the rings based on it.
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Old 20th January 2006, 11:54   #44
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Quote:
Originally Posted by santosh.s
I checked with the maruti dealer, but they can't help it. I met a service manager who was quite co-operative, took me to the workshop to understand what exactly I need. But he said he can not get those rings made. However, he offered to lift the car and adjust run-outs if any, though! Since that wouldn't be a permanent solution, I didn't do that.

Then I visited "pitstop" guys as suggested by Ajay. He said he can make hub rings (asked for Rs 300 per ring for aluminium material, that adds to the cost of alloys which is already a costly affair, especially in bangalore!). I am waiting for my 5th alloy before putting rings. (one of the piece in the set was "showroom" piece with small chippings, which I had to reject and demand a new replacement)

One good thing was that the guy said he will firmly fix those rings to alloys, so that you need not worry about misplacing... don't know how. For directions- take the road below richmond circle flyover wing towards KH road (lalbag), pitstop is located at the next signal that you find under the bridge itself.
Forgot to add this in my last reply. I think you must not pay anything more than Rs 250 per piece for the aluiminium ones'.
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Old 20th January 2006, 12:18   #45
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Quote:
Originally Posted by rev_hard
hi everyone,

my 2005 zen's steering wheel starts to vibrate at around 75-80 kph. do i need "the rings" or any other solution is available. what specifications do the rings need to be to solve this problem. also, are these rings available somewhere in south delhi.

tyre size is 175/60r14 ( as of now) but i'm going in for 185/45r14 this saturday or sunday max.

please help,

regards
anuj
You may need rings only if you are using after-market alloys which usually have large center bore. In case you are using stock rims or MGA alloys, the problem is somewhere else... probably bent rims
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