[bajica]

A little background for this thread.

My Indica Vista is now 43000+ kms. Running on stock tires since it was bought in 2008. The stock tyres had been Goodyear GT3 175/65R14 which worked perfectly till now. Only 2 punctures overall in 5 tyres over this period. All the tyres have been regularly balanced, aligned and rotated along with the spare tyre. My riding is mostly on highways and that too sedated driving at around 80-90KMPH speeds.
My old tyres still there with me.


At around 39000 kms, one of the tyres deformed and was giving a very bumpy ride. Changed it with the spare and drove it for another 1000+ kms. All tyres still were looking good, except the spare(deformed) one and would have given me around 5000+ kms.
Here is the remaining tread on the tyre.


Here started my drive to look for new tyres. Went through fellow BHPians threads and experiences about different tyre manufacturers. Thought about finalising one from MRF and Michellin.

Just about this time also got the thought of upgrading the rims too. Since TATA Manza comes with bigger rims and tyres and could not see any major change in the wheel well of VISTA and MANZA, went ahead with the bigger rims of Manza. Now came the dilemma of which tyre size on 15" wheels. Got the options of OEM of Manza 175/65R15. Since there was no where I could get advice about the upsize, decided to first change just the front wheel rims alongwith tyres of 175/65R15 Michelin make. Took these second hand. Decided to drive this setup for 200 kms and would then move onto new tyres for 15" rims. After the initial drive of 200 kms, felt confident enough and got another set of 15" manza rims and fitted them with new Michelin tyres 185/65R15 XM2. Did the balancing and alignment on all four wheels.
So the final setup was like this,
Front wheels- XM2 185/65R15,
Rear wheels - XM1 175/65R15.

Front wheel and size.



Rear Wheel.


Spare wheel is still the company original GT3 175/65R14, which will be changed over to 15" very soon. Full cost for this whole upgrade including the 4 rims and 4 tyres is around Rs.15000.

[sushantr5]

What is difference in terms of handling and ride quality? Why shift to 15"?

[bajica]

Handling is still the same. Only the ride quality has improved by around 40%+. Feel less of the tyre noise.
Only one major reason for shifting to 15" was to improve mileage which has gone up by 7%.

[GTO]

Can't say you've made the right decision here, buddy.

Originally Posted by bajica

Since there was no where I could get advice about the upsize

Link

Front wheels- XM2 185/65R15,
Rear wheels - XM1 175/65R15.

Firstly, your front tyres have a diameter that's nearly 7% overshot. It's generally recommended to stick within a 2% difference from the OEM. Even the Manza is equipped with 185/60 R15.

Then, I don't understand why you are running a different diameter on the front & rear wheels. There really is no advantage, and the car will look funny too. Lastly, you can't rotate tyres in the most efficient way.

Spare wheel is still the company original GT3 175/65R14

You cannot use this tyre because its a different diameter! It will adversely affect your car's on-road behaviour and the mechanicals too.

Originally Posted by bajica

Only the ride quality has improved by around 40%+. Only one major reason for shifting to 15" was to improve mileage which has gone up by 7%.

Actually, that is your speedometer error.

Usually when upsizing wheels, ride quality goes a notch lower. However, because you've chosen the wrong size (and the sidewall is 7mm taller), your ride quality would have improved a bit (but certainly not 40%).

Source

[directinjection]

Originally Posted by GTO

Firstly, your front tyres have a diameter that's nearly 7% overshot. It's generally recommended to stick within a 2% difference from the OEM. Even the Manza is equipped with 185/60 R15.

The key word in your quote is "generally recommended". If it's a European car, that 2% figure is very much valid. However, most Indian cars have (a) significantly raised suspensions to take care of pot-holed roads and (b) are under-tyred for fuel economy & to permit greater tyre/suspension travel. So one can go beyond 2% also but by how much would depend on the car in question. Vista is heavily under-tyred and its wheel wells are humongous (they look so disproportionate to the wheels) and so it might well absorb 7% upsize without fouling!

Originally Posted by GTO

Then, I don't understand why you are running a different diameter on the front & rear wheels. There really is no advantage, and the car will look funny too. You cannot use this tyre because its a different diameter! It will adversely affect your car's on-road behaviour and the mechanicals too.

Here I fully agree with you.

[GTO]

Originally Posted by directinjection

The key word in your quote is "generally recommended". If it's a European car, that 2% figure is very much valid. However, most Indian cars have (a) significantly raised suspensions to take care of pot-holed roads and (b) are under-tyred for fuel economy & to permit greater tyre/suspension travel. So one can go beyond 2% also but by how much would depend on the car in question. Vista is heavily under-tyred and its wheel wells are humongous (they look so disproportionate to the wheels) and so it might well absorb 7% upsize without fouling!

It "might", but what really is the point? What is the advantage? The safest would be to opt for the tried & tested Manza size.

1. A 7% difference means your speedometer (less important) and odometer readings (VERY important) go for a complete toss.

2. The Vista has very good ride quality in stock form, so it's not like the extra sidewall was required.

3. The Vista doesn't have excessive power. By going for larger wheels AND taller tyres, you've added unnecessary weight.

4. The car is now running an overall ratio that is taller. That could accentuate turbo lag a bit more and also affect city driveability.

[greenhorn]

Interesting. Do your tyres foul with the wheel wells/arches at full lock?

[bajica]

Originally Posted by GTO

Can't say you've made the right decision here, buddy.

Then, I don't understand why you are running a different diameter on the front & rear wheels. There really is no advantage, and the car will look funny too. Lastly, you can't rotate tyres in the most efficient way.

The different tyre sizes are because of my experimentation. As I have said before, I bought 2 rims with tyres secondhand to test the setup in the first place. Since those old tyres are rear tyres, they will be replaced at the earliest with new ones matching the front tyre sizes.
Since the Wheel arch is bigger, there is no visible difference in the car with regards to the wheels. I would try to capture an image and put it up.

Originally Posted by GTO

You cannot use this tyre because its a different diameter! It will adversely affect your car's on-road behaviour and the mechanicals too.

As I have said this is a spare tyre and would not be used unless in a emergency of a tyre puncture, wherein it would be rechanged after the puncture is attended to.

Thanks GTO for pointing out the irregularities, which is a learning point for me.

Originally Posted by greenhorn

Interesting. Do your tyres foul with the wheel wells/arches at full lock?

I have not experienced it till now even with full load of five people in car along with luggage over a distance of 500 kms.

[bigben]

Could you post some pics of the side profile? Would love to see how it looks.