Author Topic: Maximum Tyre Diameter  (Read 1102 times)

madbaz82

  • Registered Member
  • *
  • Posts: 5
  • Country: gb
  • My Honda: 2010 Jazz 1.2 Si
Maximum Tyre Diameter
« on: December 01, 2021, 10:31:59 PM »
Hi everyone,
This is my first post here so please take it easy on me.

In couple of weeks I will be setting off for a longish tour outside UK. I need some winter boots for my Jazz. Currently it is wearing 185/55 R16 (6J rim). Ideally I should go for 15 inch steel rims and higher wall tyres but I will be keeping the same rims this time.
It is recommended to go for thinner tyres. That leaves only 175 on the table, which is fair enough. But I cant find anywhere any advice about the tyre diameter. Lets assume we stick with the same width and play just with ratios to keep things simple for my simple brain. Then, my alternatives would be either 185/60 or 185/50 (to stay within recommended 3% difference from original).

Two questions:

1) We already know that thinner is better, but which total wheel diameter is more beneficial for driving on snow and slush? Larger or smaller? And why?

2) Currently my wheels are 610mm in diameter and there is still a bit over an inch clearance from the arch.
If for some reason thin but large wheel rolls better in winter, what maximum diameter I could go for without danger of rubbing the arches, loaded or cornering?

Many thanks for the input.

aphybrid

  • Approved Member
  • *
  • Posts: 474
  • Country: gb
  • Fuel economy: 54.46
  • My Honda: Jazz Crosstar Shiny Grey
Re: Maximum Tyre Diameter
« Reply #1 on: December 02, 2021, 06:09:27 AM »
Why not just winter tyres of same size as is?

I have done that with several Jazz & an Accord.

This will keep you completely 'legal' and meeting OEM specifications.

madbaz82

  • Topic Starter
  • Registered Member
  • *
  • Posts: 5
  • Country: gb
  • My Honda: 2010 Jazz 1.2 Si
Re: Maximum Tyre Diameter
« Reply #2 on: December 02, 2021, 07:07:31 AM »
Because in winter you encounter different conditions than hard and dry surface, and changing the size will improve traction.
If i am changing the tyres anyway, I might as well get the best possible size.

aphybrid

  • Approved Member
  • *
  • Posts: 474
  • Country: gb
  • Fuel economy: 54.46
  • My Honda: Jazz Crosstar Shiny Grey
Re: Maximum Tyre Diameter
« Reply #3 on: December 02, 2021, 11:08:15 AM »
I think given the car type, the {small} variations in speed/distance indications and the fact you have to ask the questions surely points to keeping as near standard as possible and unless to meet the many variations you state you are going to constantly change wheel/tyre size is it really necessary to further complicate a simple solution?

From AA on the subject- highlights added
"Insurance questions
There should be no need to tell your insurer if you fit winter tyres to your original wheels, even though the speed index might be lower.

The tyre speed index is still likely to exceed national speed and isn't checked as part of the car MOT test.

If you use a second set of wheels for your winter tyres you shouldn't need to tell your insurer as long as the wheels are of the correct specification:

Wheel diameter, width and offset must all meet the vehicle manufacturer's spec.
Check your handbook for wheel and tyre sizes suitable for your car.
We've heard stories of insurers raising premiums or remarkably even refusing cover if winter tyres are fitted but this shouldn't be the case any more.

The Association of British Insurers (ABI) published a commitment setting out the position of some named insurers on premiums and winter tyres.

Check the ABI's list as some insurers require you to tell them you've fitted winter tyres even though your premium or cover won't change.

Insurers' commitment and list of insurers"

madbaz82

  • Topic Starter
  • Registered Member
  • *
  • Posts: 5
  • Country: gb
  • My Honda: 2010 Jazz 1.2 Si
Re: Maximum Tyre Diameter
« Reply #4 on: December 02, 2021, 01:00:20 PM »
Thank you. That is a very good point.

aphybrid

  • Approved Member
  • *
  • Posts: 474
  • Country: gb
  • Fuel economy: 54.46
  • My Honda: Jazz Crosstar Shiny Grey
Re: Maximum Tyre Diameter
« Reply #5 on: December 02, 2021, 04:35:57 PM »
You will find a very noticeable effect of a straight swap to winter grade tyres of the same size, the basic material composition provides the ability of the tyre to stay soft in the colder temperatures giving improved grip so this will be better for all road surfaces.
Also the sips retain more snow giving better grip - why a snowball stays together.

Look here from Barum https://www.barum-tyres.com/car/expert-advice/tyre-knowledge/how-do-winter-tyres-work
« Last Edit: December 02, 2021, 04:42:40 PM by aphybrid »

culzean

  • Approved Member
  • *
  • Posts: 8017
  • Country: england
Re: Maximum Tyre Diameter
« Reply #6 on: December 02, 2021, 04:45:00 PM »
You will find a very noticeable effect of a straight swap to winter grade tyres of the same size, the basic material composition provides the ability of the tyre to stay soft in the colder temperatures giving improved grip so this will be better for all road surfaces.
Also the sips retain more snow giving better grip - why a snowball stays together.

Look here from Barum https://www.barum-tyres.com/car/expert-advice/tyre-knowledge/how-do-winter-tyres-work

Our Nokian winters are quieter than some summer tyres I have had,  and give a better ride.  The steel rims save the alloys from salt and sliding into kerbs on slippery roads as well.
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

madbaz82

  • Topic Starter
  • Registered Member
  • *
  • Posts: 5
  • Country: gb
  • My Honda: 2010 Jazz 1.2 Si
Re: Maximum Tyre Diameter
« Reply #7 on: December 02, 2021, 09:08:51 PM »
You will find a very noticeable effect of a straight swap to winter grade tyres of the same size, the basic material composition provides the ability of the tyre to stay soft in the colder temperatures giving improved grip so this will be better for all road surfaces.
Also the sips retain more snow giving better grip - why a snowball stays together.

Look here from Barum https://www.barum-tyres.com/car/expert-advice/tyre-knowledge/how-do-winter-tyres-work

Thank you very much. Your answers gave me all I needed to make a good decision.

madbaz82

  • Topic Starter
  • Registered Member
  • *
  • Posts: 5
  • Country: gb
  • My Honda: 2010 Jazz 1.2 Si
Re: Maximum Tyre Diameter
« Reply #8 on: January 02, 2022, 01:01:12 PM »
Just a quick update for the final conclusion.

In the end I went for 185/60 R16.

This was just 17mm more in tyre diameter and just one notch above recommended by manufacturer.
The speedo finally shows exactly the speed I am driving at, and the drive is much much more comfortable without feeling even smallest bumps and pebbles anymore.
When changing back to all-year-rounds I will stick to this size.

I wanted to thank everyone for the input and helping me to find exactly wat I needed   :D

culzean

  • Approved Member
  • *
  • Posts: 8017
  • Country: england
Re: Maximum Tyre Diameter
« Reply #9 on: January 02, 2022, 01:05:03 PM »
It is a continuing myth that proper snow tyres work better on snow if they are narrower, this is a throwback to days when the really thin tyres without proper tread could use the higher ground pressure of a narrow tyre to force its way through snow down to the road surface for grip.  Modern snow tyres actually grip the snow,  and the wider the better - just look at the dedicated arctic vehicles with either wide caterpillar tracks or huge low pressure balloon tyres.  Beware the insurance company if you have a prang...

European countries accept all season tyres in snow areas
« Last Edit: January 02, 2022, 03:49:41 PM by culzean »
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

Tags:
 

anything
Back to top