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Old 26th August 2007, 00:54   #31
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Originally Posted by shrivz View Post
I think its best to stick to the Factory recommended tyre pressure. Manufacturers are not fools. A lot of R&D is done before they come to the conclusion for a recommended tyre pressure. Increasing / Decreasing tyre pressure will cause uneven wear on your tyres.
A substantial increase/decrease will indeed cause uneven wear. What I am wondering is if the pig squeals experienced by d_himan is a symptom of underinflation. I think excessive sidewall deformation in fast cornering with underinflated tyres can cause those pig squeals.

Last edited by rks : 26th August 2007 at 01:05.
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Old 26th August 2007, 01:21   #32
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@ RKS - Quite right - this incident could have been caused certainly by under inflation with side walls worn off !!

Many people do not change their stock rubber for a long time. Could be a one-off with your car - else more people would have come forward with this problem. Anyways - good to hear that you are safe - it is a scary situation !! Cheers !!
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Old 27th August 2007, 11:26   #33
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Thanks so much for the concern guys...a few clarifications from my end...

1. The tread is perfectly ok - no signs of wear/tear
2. I put 33 PSI all around, once every week
3. Always thought FWD cars respond well to gentle acceleration throughout a S-Curve...shall get into the gore of FWD dynamics to understand better!
4. Yes, will upgrade..the dealer tells me that the warranty/insurance would go for a toss...but then, I reckon good tyres are a better insurance!
Thanks!
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Old 27th August 2007, 11:42   #34
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Thanks Nitrous, yep 195/65 was recommended by Lal Enterprises, Chennai as well. Might go with the same..was just wondering if ground clearance would be adversly affected due to a reduced profile..
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Old 27th August 2007, 11:43   #35
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What I am having in mind is that the tread in your front tyres may be wearing out much faster and you may have rotated your tyres recently. In which case the situation is ripe for oversteer, with much lower grip in the rear tyres.
Upon experiencing oversteer in FWD cars, opposite lock is not recommended and neither should you accelerate immediately, as these moves will increase the fish-tailing effect. What you should do is steer the car in the direction you want to go in and initially take your foot off the pedal; avoid braking hard, but brake lightly only if necessary. When the car slows down enough, the rear wheels will get some traction and the oversteer will begin to correct itself; *then* immediately accelerate out of the turn, once your car is going in the right direction. The acceleration will transfer some weight on to the rear wheels and tend to correct the car out of oversteer. Oversteer in FWD's is technically more difficult to handle than in RWD's.
Some more points. There are two kinds of oversteer that one should be concerned about. The first one, which applies to this case, is called "power oversteer". This happens when the rear wheels lose traction when one approaches a curve too fast. Normally it should not happen in FWD, as the car is usually set up to understeer before the power oversteer can happen. I think when the rear wheels have less tread or are not correctly inflated, a power oversteer could happen in a FWD. The solution is basically what I posted above. Ease the throttle initially; while this causes undesirable transfer of weight to front wheels, it does also attack the cause of the oversteer, namely excessive speed. Turn in the direction you want to move in, but do not aggressively apply opposite lock and then immediately accelerate as the car might start fishtailing. Finally, accelerate out of the turn when the car is pointed in the right direction.

The second type of oversteer is called "lift off" oversteer. This happens when one approaches a bend fast, and midway through the turn, suddenly lifts off the foot from the throttle. The transfer of weight to the front wheels can sometimes cause the rear wheels to lose traction. In this case the solution is to steer in the direction one wants to move in and then accelerate. This is a less serious type of oversteer and could be only momentary as the car slows down.

Last edited by rks : 27th August 2007 at 11:49.
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Old 27th August 2007, 12:02   #36
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Hi d_himan,

The kind of driving mentioned is definitely asking for trouble. And endangering lives. You're really lucky that nobody got hurt. You might not be as lucky next time.

There is absolutely no excuse for cornering at such speeds and blaming tyres, Maruti etc. Here, its clearly driver at fault. Maruti does not expect its cars to be driven in such a manner on Public roads.
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Old 27th August 2007, 12:13   #37
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Hi d_himan,

The kind of driving mentioned is definitely asking for trouble. And endangering lives. You're really lucky that nobody got hurt. You might not be as lucky next time.

There is absolutely no excuse for cornering at such speeds and blaming tyres, Maruti etc. Here, its clearly driver at fault. Maruti does not expect its cars to be driven in such a manner on Public roads.

Agree with you Risga. My fault....hell, its so easy to get carried away. Narrowly missed a couple on a two wheeler - I never could have forgiven myself if they had got seriously injured.
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Old 27th August 2007, 12:23   #38
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Here's my recommendations:
...
2.Don't miss the upcoming track day in chennai and learn the dynamics of cars while driving fast.
whens trackday in chennai again?
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Old 27th August 2007, 14:45   #39
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rks... thanks for your great hints and explanations, but I have a query..

I have been under the impression that it is slowing by braking that throws weight forwards, thus reducing the rear-wheel traction. I thought that slowing by engine-braking (ie, taking foot off the gas) did not. Consequently the "feet off everything until the car gets a grip again" again.
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Old 27th August 2007, 15:46   #40
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Originally Posted by Thad E Ginathom View Post
I have been under the impression that it is slowing by braking that throws weight forwards, thus reducing the rear-wheel traction. I thought that slowing by engine-braking (ie, taking foot off the gas) did not. Consequently the "feet off everything until the car gets a grip again" again.
That is a pretty safe option for most of us. Accelerating through a skid is generally for experts.

The weight will get thrown forward whenever there is a substantial deceleration. So if you are accelerating hard at high speed and then suddenly lift your foot off the throttle, there will be some weight transfer to the front wheels. But I suspect that for this to cause oversteer in a FWD, you would need a pretty capable car, high speeds and/or bad rear tyres.

Last edited by rks : 27th August 2007 at 15:48.
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Old 27th August 2007, 17:07   #41
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Quote:
Originally Posted by rks View Post
That is a pretty safe option for most of us. Accelerating through a skid is generally for experts.

The weight will get thrown forward whenever there is a substantial deceleration. So if you are accelerating hard at high speed and then suddenly lift your foot off the throttle, there will be some weight transfer to the front wheels. But I suspect that for this to cause oversteer in a FWD, you would need a pretty capable car, high speeds and/or bad rear tyres.
Very true. Sudden deceleration will result in the load transfer being front-biased. However, oversteer in a FWD/RWD really depends on the suspension setup and/or the driver. A FWD can be easily setup for oversteer- especially the lift-off type. However, I doubt if our stock Swifts are setup for the same.

Here is Tiff Needell sliding the rear end of a Civic Type R- Amazing car control are least words one can use.



Regarding under sized tires; I don't know why Maruti under-tires almost all their cars. My Dad's Baleno came shod with 165s which are insufficient to say the least. Any possibility of a late and sharp turn-in are dismissed. The other day I was at a roundabout (3 AM in the night) and I tried to push the car a bit and initiate a quick left-right to negotiate the S-bend. As soon as I fed the required steering input for the left flick, the car lost grip and started sliding. By reflex action, I immediately fed opposite lock. The car then fishtailed in the opposite direction and once I went back to the gas again; the tires got grip and the car moved forward in the intended trajectory. My heart was in my mouth for those few seconds.
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Old 27th August 2007, 17:15   #42
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Originally Posted by d_himan View Post
Hi everybody!

I own a Oct '06 Swift VXi with around 9100 Km on the odo. Always hated the original 165/80 JKs. But off late, though the pig-squeals on corners/noisy entrances into smooth hotel foyers were entertaining/embarassing, the lack of grip always worried me slightly.

Yesterday, my worst fears were realized. I was going into a S-Curve at around 80+ kmph (traffic was sparse), accelerating in 3rd gear. In my earlier Ikon 1.6 SXi, I wouldn't even think twice to do it at 120 kmph.
As usual, the tyres started squealing and I didn't pay attention. Suddenly, the rear grip was gone and the car oscillated to the left. I quickly applied the requisite opposite lock and accelerated, but this in turn created a fish-tail effect - a left to right swaying. I just about missed hitting a two wheeler and my whole life flashed before me! Quickly, I did a handbrake turn, turned a full 180 degrees, faced the traffic (thankfully, sparse) and stopped the car. Probably, that saved my life and those of fellow commuters around me.

My advise no. 1 - if you enjoy driving hard and cornering hard, forget the warranty/insurance invalidity fears, get yourself some decent rubber for the Swift Vxi...its a death trap otherwise.

Regards,
Himan
hope you upgrade the tyres soon, safe and happy driving to you.

Jaggu
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Old 27th August 2007, 17:44   #43
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Accelerating into a curve with the stock swift tyres will defanitely cause the back to fish tail..i have been through that in a swift. the best way as many have mentioned is to go into a curve slow and come out of it fast. All tyres have limitations while accelerating through a curve, the stock tyre on swift might fishtail at 80KMPH but a broader and better quality tyre will fish tail may be at 100kmph, so it is important to respect the limits of the tyre.
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Old 27th August 2007, 23:04   #44
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Good that yu came out safe. Take care.
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Old 28th August 2007, 18:05   #45
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Thank god, it didn't turn ugly. For Swift, the stock tyres are totally inadequate.
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