[Vid6639]

Originally Posted by koushik

Track does change with different tyre size. I suggest you to go through the official website of Maruti Swift .Here for ZXI variant the front and rear track is 1520 mm (185/65 R15 ) where as for LXI variant the front and rear track is 1530 mm ( 165/80 R 14). Similarly the track in nexon XM is wider for 195/60 R16 than that of 215/60 R 16 variant. If the track does not change then total width will go on changing which would alter many things.

Hey Koushik, you are right the track is changing for Nexon XM vs XZ but it is not due to the tyre size.

The reason is due to the rims. The lower variant of Nexon as well as Swift have steel wheels which have a different rim offset vs the alloy wheel. The different offset results in centre of the wheel changing hence the change in track.

If the rim is same and you upsize tyres, your track will not change.

You can only change tyre width upto a certain limit for a particular rim. any more than that then you need to change rim with different width and offset which changes the track.

[koushik]

Originally Posted by Vid6639

Hey Koushik, you are right the track is changing for Nexon XM vs XZ but it is not due to the tyre size.

The reason is due to the rims. The lower variant of Nexon as well as Swift have steel wheels which have a different rim offset vs the alloy wheel. The different offset results in centre of the wheel changing hence the change in track.

If the rim is same and you upsize tyres, your track will not change.

You can only change tyre width upto a certain limit for a particular rim. any more than that then you need to change rim with different width and offset which changes the track.

While designing alternate rims for alternate tyres the main point is that the total width on ground ( which includes both the tyres ) should remain unchanged. So if the track is kept fixed then total width on ground will go changing with different tyres.

[Vid6639]

Originally Posted by koushik

While designing alternate rims for alternate tyres the main point is that the total width on ground ( which includes both the tyres ) should remain unchanged. So if the track is kept fixed then total width on ground will go changing with different tyres.

Not really the width but the clearance with suspension. If you increase the width of the tyre on same rim track wont change, however you cannot increase the width beyond a point as you will not have enough clearance with suspension components, hence you need to change the rim with diff offset to accommodate the wider tyres.

What I am trying to say is track will not change just by changing the tyres. Track changes when you change the rims with diff offset.

For example, my car has a stock size of 195/65-15. However I changed the tyres to 205/65-15. Even though my tyres are 205 vs 195mm the track of the car remains the same with either set of tyres.

However if I go for 215 or 225, I will need to change the rims with a wider rim as well as different offset.

[condor]

Originally Posted by koushik

While designing alternate rims for alternate tyres the main point is that the total width on ground ( which includes both the tyres ) should remain unchanged. So if the track is kept fixed then total width on ground will go changing with different tyres.

Like Vid6639 said, the track does not change. If you are using stock rims or stock alloys, the track should remain same. This is because wider tyres will increase the width on both sides of the centre line. The mounting plane (of the rim) is still the old one, and a wider tyre will still fit on the same rim, but protruding a little more on each side of the centre line of the wheel.

[koushik]

Originally Posted by condor

Like Vid6639 said, the track does not change. If you are using stock rims or stock alloys, the track should remain same. This is because wider tyres will increase the width on both sides of the centre line. The mounting plane (of the rim) is still the old one, and a wider tyre will still fit on the same rim, but protruding a little more on each side of the centre line of the wheel.

I agree that track will not change by using wider tyre on the same rim . But wider tyre will increase total width on ground ie. track plus additional half parts of tyre width. So total width will go on increasing with use of wider tyres.
My point to tell is that with various options of tyres offered for the same model , though the track is slightly changed by different configuration of rims , the ultimate width on ground is kept fixed.

For example , the day before I got delivery of Nexon XM with 195/60R16 tyre. When measured , it had the same total width on ground ( point to point measurement between outer line of tyre prints on clean surface) as that with 215/60R16 . This is not possible if the wheel rim is same in both the cases. So the steel rim for Nexon XM is designed in a way that though it increases ( for example) front tread to 1550 mm( against 1540 mm for top model with 215/60R15) the total width between two front tyres ( including entire tyre prints ) on ground remains the same for both the variants.

[rajivtelang]

Originally Posted by koushik

For example , the day before I got delivery of Nexon XM with 195/60R16 tyre. When measured , it had the same total width on ground ( point to point measurement between outer line of tyre prints on clean surface) as that with 215/60R16 . This is not possible if the wheel rim is same in both the cases. So the steel rim for Nexon XM is designed in a way that though it increases ( for example) front tread to 1550 mm( against 1540 mm for top model with 215/60R15) the total width between two front tyres ( including entire tyre prints ) on ground remains the same for both the variants.

Could somebody help to understand the stability part with different tyre size (between XZ+ and XM) and reduced GC with 195/60 R16? Even if the treads remain the same, surely the contact area will reduce with 195 tyres, GC will reduce due to 60% aspect ratio (by 12mm) and hence the center of gravity will be lowered. In fact with smaller tyre width the stability at high speed will reduce but with lower center of gravity it will increase. Did anybody notice this difference between XZ+ and XM? Are they compensating each other? If yes, it is a very good piece of engineering from TATA.

[koushik]

Originally Posted by rajivtelang

Could somebody help to understand the stability part with different tyre size (between XZ+ and XM) and reduced GC with 195/60 R16? Even if the treads remain the same, surely the contact area will reduce with 195 tyres, GC will reduce due to 60% aspect ratio (by 12mm) and hence the center of gravity will be lowered. In fact with smaller tyre width the stability at high speed will reduce but with lower center of gravity it will increase. Did anybody notice this difference between XZ+ and XM? Are they compensating each other? If yes, it is a very good piece of engineering from TATA.

I can add one point. The recommended tyre pressure for 215/60R16 is 30 PSI where as for 195/60R16 it is 32 to 34 PSI . The increase in tyre pressure can reduce the gap between GC of both the variants. As for the stability factor 195/60 R 16 is perfect. There is no additional benefit of using 215/60 R16 except it's big look. Simple visual observation can not differentiate between the two types of tyres !

[roy_libran]

Originally Posted by koushik

There is no additional benefit of using 215/60 R16 except it's big look. Simple visual observation can not differentiate between the two types of tyres !

1. Notwithstanding differential air pressure, there is exactly a difference of 1" on the overall diameter between the two sizes, which translates to a 0.5" difference approximately, in effective ground clearance. Whether that is a benefit or a shortcoming, completely depends on the Use Case.

2. Secondly, there is a 20mm increase in contact patch, which translates into better grip, more rolling resistance and lesser economy. Again whether it's a benefit or not, is subjective.

3. Fitting in the 215 section in the same wheel well, despite the additional 0.5" margin due to GC will necessitate more negatively offset rims, which, alongside the increase in off centered rolling mass, will lead to an earlier failure of the wheel bearing than for the 195 section. That's a trade off, minor in my books, but may not be for some others.

4. The 215 section tyre will give you a substantially better contact patch on a slipping surface, especially when you reduce the pressure, and will allow the vehicle to proceed in situations where it's 195 section sibling won't. At the same time, someone else, may have more use of the reduced GC of the 195 section, but should once really be pushing a cross over to that limit?

It's not just about the looks, its functional - just not for everyone.

On a separate note - Can someone please suggest any AT tyres for the 215 section? I want to change the stock tyres outright, when I pick my vehicle this weekend.

[koushik]

Originally Posted by roy_libran

1. Notwithstanding differential air pressure, there is exactly a difference of 1" on the overall diameter between the two sizes, which translates to a 0.5" difference approximately, in effective ground clearance. Whether that is a benefit or a shortcoming, completely depends on the Use Case.

2. Secondly, there is a 20mm increase in contact patch, which translates into better grip, more rolling resistance and lesser economy. Again whether it's a benefit or not, is subjective.

3. Fitting in the 215 section in the same wheel well, despite the additional 0.5" margin due to GC will necessitate more negatively offset rims, which, alongside the increase in off centered rolling mass, will lead to an earlier failure of the wheel bearing than for the 195 section. That's a trade off, minor in my books, but may not be for some others.


4. The 215 section tyre will give you a substantially better contact patch on a slipping surface, especially when you reduce the pressure, and will allow the vehicle to proceed in situations where it's 195 section sibling won't. At the same time, someone else, may have more use of the reduced GC of the 195 section, but should once really be pushing a cross over to that limit?

It's not just about the looks, its functional - just not for everyone.

On a separate note - Can someone please suggest any AT tyres for the 215 section? I want to change the stock tyres outright, when I pick my vehicle this weekend.

This is true in theory. When it comes to practicality particularly for nexon , the difference is negligible .

[roy_libran]

Originally Posted by koushik

This is true in theory. When it comes to practicality particularly for nexon , the difference is negligible .

Theory? Ask Off-roaders how much they spend for a 20 mm contact patch and 25 mm GC increase when upgrading tyres. It’s a substantial difference, and the % difference is more on a 25 inch tyre, than on the typical 30/31 inch tyre for off road vehicles.

[koushik]

Originally Posted by roy_libran

Theory? Ask Off-roaders how much they spend for a 20 mm contact patch and 25 mm GC increase when upgrading tyres. It’s a substantial difference, and the % difference is more on a 25 inch tyre, than on the typical 30/31 inch tyre for off road vehicles.

OK sir , we were discussing Nexon. You mean to say Nexon with 215/60R16 tyre has far more off road capability than other variants ?

[roy_libran]

Originally Posted by koushik

OK sir , we were discussing Nexon. You mean to say Nexon with 215/60R16 tyre has far more off road capability than other variants ?

Yes Sir - As far as Cross overs go. But looking at the nuances, the 195 may have an edge in slush due to narrower track.

But that comes at other costs, as I have pointed out earlier.

[rajivtelang]

Originally Posted by roy_libran

Yes Sir - As far as Cross overs go. But looking at the nuances, the 195 may have an edge in slush due to narrower track.

But that comes at other costs, as I have pointed out earlier.

Do the steel rims support 215 wide rubber? This is to save some money in case one wants to switch to that without having to change to alloys.

Also during the TD I found the clutch to be slow to respond while releasing it after a gear is switched. It comes back slowly once released causing completely different driving style and not comfortable. I confirmed it with videos on You-Tube. Could somebody confirm the same here? And what could be the reasons and solution?

[roy_libran]

Originally Posted by rajivtelang

Do the steel rims support 215 wide rubber? This is to save some money in case one wants to switch to that without having to change to alloys.

Also during the TD I found the clutch to be slow to respond while releasing it after a gear is switched. It comes back slowly once released causing completely different driving style and not comfortable. I confirmed it with videos on You-Tube. Could somebody confirm the same here? And what could be the reasons and solution?

Give me a week to answer that. I'm taking delivery of the XMA on Sunday (fingers crossed), which has steel rims with 215 section tyre. I'll then be able to comment whether or not they are the same wheels.
No clue on clutch, because my candidates were all clutchless.

[rajivtelang]

Originally Posted by roy_libran

No clue on clutch, because my candidates were all clutchless.

Not happy with Tata's sales . I was trying to get the answers to most of the questions I raised here from the SA. He had promised me to provide the details by Sunday (including accessories available). As expected he never got back. On Monday he called me and asked what have I decided (Kind of weird since I was waiting for info from him). He promised to get it by EOD Monday. No response and few minutes back today got a call from a lady asking same question, what have you decided about Nexon. Not sure if I have to laugh or reconsider going for a TATA vehicle (KHT motors, Domlur). I know Team BHP will provide all info needed here but SA has to do his job as well (if not smart enough he can refer to team BHP as well ), not sure if they are there for only paper work while selling the cars.

Has anybody observed this kind of strange out of sync and haphazard behavior from Tata sales?