[headers]

Originally Posted by Nikhilb2008

The contact patch has increased by 10mm but 10mm is very small. In reality, there may not have been an increase at all! When a tyre says 185mm, it may not be exactly 185mm. It may be a little more or a little less.

How much more or less Nikhil from your experience? 40% more or 10% less?

Can you throw pointers how to increase contact patch on tyres? Does Tyre pressure play a role?

[Nikhilb2008]

Originally Posted by bala80

I recently upgraded from 185/65/15 - apollo aceleres to 195/60/15 yoko c-drives on my vento. The ride quality has improved and noise has gone down which is only expected, but the surprise is - my steering has become lighter inspite of increased contact patch and the play in the steering has increased. It isnt direct as it was earlier and moves around towards left and right without any directional change to the tyres. I replaced these new tyres couple of days back and have done around 100 kms on them, overall the car has done around 5500 km's. Balancing was checked when these new tyres were installed.

Is this something to do with alignment? Can someone suggest what could be the possible reason behind this?

Originally Posted by headers

How much more or less Nikhil from your experience? 40% more or 10% less?

Can you throw pointers how to increase contact patch on tyres? Does Tyre pressure play a role?

Tyre pressure plays a role. Also, there is no fixed ratio or anything. For example, a 195/60-14 Yokohama A drive looks substantially thinner than a 195/60-14 Ad07. It also depends on the shape of the tyre and the design.

[headers]

Originally Posted by Nikhilb2008

Tyre pressure plays a role. Also, there is no fixed ratio or anything. For example, a 195/60-14 Yokohama A drive looks substantially thinner than a 195/60-14 Ad07. It also depends on the shape of the tyre and the design.

Thanks Nikhil - I'm aware of that.

What I wanted is the basic shapes of the tires in the market and various improvements / design improvements of each tyre over its competitor!!

For Instance, Michelin XM1+ looks fatter than a similar sized Pirelli or Goodyear because of....

[Nikhilb2008]

I have no idea. It is just the design of the tyre, the shoulder.

[bala80]

Thank you Nikhil for your response. I was under the impression, may be this is due to the alignment, but very disappointed to note this is the characteristic of C-drives. Also surprised that not many owners have reported about this behaviour in their reviews.

I'm very unhappy with this change, my steering has become very vague and has lost the directness that it had before, it has taken lot of fun from driving. I feel I have to turn the steering lot more to change direction compared to the apollo's earlier. Does primacy LC or Turanza's fare better in this respect?

Originally Posted by Nikhilb2008

This is due to the C drives. I felt the same thing in our old NHC Vtec. The C drives are mainly comfort tyres and the steering feels a little vague sometimes. It has nothing to do with the alignment. The contact patch has increased by 10mm but 10mm is very small. In reality, there may not have been an increase at all! When a tyre says 185mm, it may not be exactly 185mm. It may be a little more or a little less.

[Nikhilb2008]

Turanzas are a little better. Primacy LCs, I'm not too sure.

[Monaro CV8]

Hi Nikhil,
Wanted to take your advice on the uneven wear on the treads of my A-drives (205 55 R15 - Octy 1.9TDi).
The fronts are wearing on the outer rim (towards the wheel) & the rear tyres are wearing out on the inner side.
I know that tyre rotation is a way to get around these nuances, but I would like to inquire, that why does this happen in the 1st place?
Thanks in advance mate.
cheers.

[Nikhilb2008]

Originally Posted by Monaro CV8

Hi Nikhil,
Wanted to take your advice on the uneven wear on the treads of my A-drives (205 55 R15 - Octy 1.9TDi).
The fronts are wearing on the outer rim (towards the wheel) & the rear tyres are wearing out on the inner side.
I know that tyre rotation is a way to get around these nuances, but I would like to inquire, that why does this happen in the 1st place?
Thanks in advance mate.
cheers.

Could be anything. Wrong toe, wrong camber. Without a proper alignment report, it's difficult to say anything.

[Nikhilb2008]

A lovely video I found on youtube on why alignment changes.

Hunter's What Causes Alignment To Change? - YouTube

Also found a really nice video about why people still have vibration issues after balancing. This also seems to be a shameless plug by Hunter to sell their top end balancers, but the information is nice and clearly explained!

http://www.youtube.com/watch?v=bjEvG...eature=related

[headers]

OK..so how do they correct the tyre runout problems? I can think of replacing the tyre..any other solution would be nice to learn!

[Nikhilb2008]

See the video. They match the rim and the tyre to minimise the effect of the runout. This can be done on the Balancer they are talking about in the video.

In India, in the real world, these balancers are almost non-existent. Most Audi and Jaguar/Land Rover dealers have them but very very few tyre shops or car service centres. They are ridiculously expensive!

[sagarpadaki]

Originally Posted by Nikhilb2008

In India, in the real world, these balancers are almost non-existent. Most Audi and Jaguar/Land Rover dealers have them but very very few tyre shops or car service centres. They are ridiculously expensive!

How much do these 3d alignment and balancing machines cost nikhil? Not the most expensive ones but the price of the hunter equipment usually used here in India

[Nikhilb2008]

3D Aligners from Hunter cost around 6.5 lakhs and go all the way to 11 lakhs for the top end. Balancers start at about 2-2.5 lakhs and go upto 6 lakhs or so for the 9700 Roadforce.

[Gansan]

Originally Posted by Nikhilb2008

In India, in the real world, these balancers are almost non-existent. Most Audi and Jaguar/Land Rover dealers have them but very very few tyre shops or car service centres. They are ridiculously expensive!

I have seen a balancer exactly like this at MSM when I go for wheel balancing/rotation/alignment. Are they so expensive?

[kpzen]

Originally Posted by bala80

I recently upgraded from 185/65/15 - apollo aceleres to 195/60/15 yoko c-drives on my vento. The ride quality has improved and noise has gone down which is only expected, but the surprise is - my steering has become lighter inspite of increased contact patch and the play in the steering has increased. It isnt direct as it was earlier and moves around towards left and right without any directional change to the tyres. I replaced these new tyres couple of days back and have done around 100 kms on them, overall the car has done around 5500 km's. Balancing was checked when these new tyres were installed.

Is this something to do with alignment? Can someone suggest what could be the possible reason behind this?

Been there done that !

The only problem with the C drives is the STEERING, which almost becomes non existent, extra light and vague.

Only solution to the problem is to run with a negative camber but downside is the tire wear on the inside.
Had them for 1000kms, did all kinds of trials with alignment and finally had to get them changed.

Other than this, the tires are quite grippy and brilliant in wet conditions.
I still have two of them running at the back.