[Chewbacca]

Originally Posted by Rehaan

Do you have a source for this information? (50% more heat / 4x the wear rate)

I read it somewhere in the attached PDF.
It does not precisely say 4x or 50% but it does provide some interesting figures on treadwear. And in another section about temperature.

Since the question was about heat built-up + high speeds, I simply approximated on the net effect of both factors combined.

[Chewbacca]

Originally Posted by Harbir

.... in other words, low pressure does not cause heat because air molecules have space to wander around and smash harder.

A quick research proves you right.
I stand corrected if the "molecules" from my post are removed

[dr.aviansh]

Kickstarting this old thread :

My car wears 165/65 R14 and is very stiffly sprung because of the heavier diesel heart. My major concerns are a plushier ride in the city and a gain in ground clearance.

I am considering a shift to 175/70 R13 which will give me a taller sidewall and some extra GC.

My two questions :

-Is one size downsizing advisable to gain a taller sidewall?

-Moving from 165 to 175 will give me a wider track. Can it make the ride more unsettled on broken roads or induce side to side jolting?

[Chewbacca]

Originally Posted by dr.aviansh

My two questions :

-Is one size downsizing advisable to gain a taller sidewall?

You will have to replace the wheels too.
Taller sidewall will make the ride a little bit comfortable but the car's cornering performance will suffer a little bit (body roll increases)

Originally Posted by dr.aviansh

-Moving from 165 to 175 will give me a wider track. Can it make the ride more unsettled on broken roads or induce side to side jolting?

Not at all. Your aim should be in reducing the weight of wheel + tyre after change. Choose rim and tyre wisely, lighter the better, and with the WIL mark

Car height will increase by 2 mm, which is quite acceptable and within safe limits

[Vikram Arya]

Originally Posted by dr.aviansh

Kickstarting this old thread :

My car wears 165/65 R14 and is very stiffly sprung because of the heavier diesel heart. My major concerns are a plushier ride in the city and a gain in ground clearance.

I am considering a shift to 175/70 R13 which will give me a taller sidewall and some extra GC.

My two questions :

-Is one size downsizing advisable to gain a taller sidewall?

No harm in that except you will have to change your wheel size as has been pointed out by the previous contributor which is an expensive proposition.

At 165/65R14 your rolling diameter is 22.4", width is 6.5", and the sidewall is 4.2".

A better & economically viable solution will be to go to 185/60/R14. At this tire size, you get to keep your existing wheels with rolling diameter at 22.7", width at 7.3" and sidewall at 4.4".

The difference in rolling diameter is +1.3% which is well within the 1.5% range.

-Moving from 165 to 175 will give me a wider track. Can it make the ride more unsettled on broken roads or induce side to side jolting?

At 185/60R14 your increase in the sidewall is 0.2" which is not much and will give you a slightly improved ride with a wider track and will not impair the handling.

At 175/70R13, the sidewall increases to 4.8" which is an almost 14% increase over the original sidewall. This will affect the cornering performance though will give you a cushy ride.

[maksins]

Dear fellow BHPians,

I had a small sidewall bulge in one of my tyres and I need to replace it. I have alloy wheels and a spare tyre with exact same size but with steel rim. The tyres are 36 months old but have done only 7000 kms. The tyres are 175/60R15

I have few questions:

1. I have not used the spare tire at all, would using it as regular tyre with alloy wheel a good idea? I plan to replace all tyres together after 4-5 years as I understand that you should replace tyres irrespective of kms because of change in rubber compound due to aging.

2. I will use the bulged tyre as spare. I have two roadside assistance subscription.

3. If indeed I have to change the tire, can I change the bulged tyre with one of the 185/60R15, 175/65R15, or 165/60R15? If yes, then which would be a better choice? This from pure financial consideration. There is only one manufacturer (Bridgestone) for my current 175/60R15, so cost is very high (6275/-), while other mentioned tyres are atleast 1500 Rs. cheaper a piece.

4. In longer term, I would like to switch to one of the three suggested tyre sizes because of competitive price and better availability.

It would be very helpful if you can provide some insight.