215-40-18 or 225-40-18 tyres on Polo GTI

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monkeyhanger
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Re: 215-40-18 or 225-40-18 tyres on Polo GTI

Post by monkeyhanger »

green justin wrote: Tue May 12, 2020 6:58 am
monkeyhanger wrote: Mon May 11, 2020 10:29 pm
green justin wrote: Mon May 11, 2020 9:36 pm
I have to ask...
I get an average +- 420km per tank , would I get similar figures if I have PS4 fitted following the same daily routes to work and back.
Let's be clear on that "420km per tank" - do you always get that, or just since the roads are empty due to Covid-19 lockdown?

420km = 262 miles, if you're taking it down to an indicated "0 miles/0 km then that's the UK equivalent of 30mpg. I was averaging 34mpg on my 13 mile commute on mixed road pre-lockdown and I was getting no better than that on the Bridgestones.
Before LockDown, I would get those figures. Between 400km to 420km then the light goes on.
Mostly Back Roads with stop and go. Sometimes Sport Mode.
Mine's always got the engine in Sport mode. No fuel savings to be had in Normal - the engine operates the same, but with a blunted throttle response, so you press the throttle harder for the same effect.
green justin
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Re: 215-40-18 or 225-40-18 tyres on Polo GTI

Post by green justin »

I am hoping moving from 215-40 tyre to 225-40 will improve ride quality.

My 5year old Complained it is very bumpy ride. She sits in a car seat.

i decided to test it out, my wife drove while i sat in the rear, :shock: it is very firm, there is no forgiveness in the sidewall.
monkeyhanger
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Re: 215-40-18 or 225-40-18 tyres on Polo GTI

Post by monkeyhanger »

green justin wrote: Fri Jun 12, 2020 1:03 pm I am hoping moving from 215-40 tyre to 225-40 will improve ride quality.

My 5year old Complained it is very bumpy ride. She sits in a car seat.

i decided to test it out, my wife drove while i sat in the rear, :shock: it is very firm, there is no forgiveness in the sidewall.
Michelins do have a more forgiving sidewall, especially with tyre pressures set to 36psi fronts and 33psi rears. Do you have the suspension set to normal rather than sport? That's a start.
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Re: 215-40-18 or 225-40-18 tyres on Polo GTI

Post by green justin »

In normal mode, and in 36 psi.
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Re: 215-40-18 or 225-40-18 tyres on Polo GTI

Post by fazzy »

green justin wrote: Mon May 11, 2020 9:26 pm
fazzy wrote: Mon May 11, 2020 8:02 pm Just got mine.... :)
Hoping for some improvement :)
Can you post more pictures a meter away?
Missed your post earlier on...
But here it is.
An unusual picture :)
Front 225/40/18 Michelins PS4, rear 215/40/18 Bridgestone T001
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Re: 215-40-18 or 225-40-18 tyres on Polo GTI

Post by fazzy »

Here is also a speedometer vs gps reading on the 225/40/18 if anybody was interested... 😉
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Re: 215-40-18 or 225-40-18 tyres on Polo GTI

Post by stuartrendall »

Adding width to the tyres wont change speedometer readings as you aren't increasing the circumference. If you put 225/50/18's on the front then you would affect the speedo.
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Re: 215-40-18 or 225-40-18 tyres on Polo GTI

Post by PhilArnold »

stuartrendall wrote: Sat Jun 13, 2020 12:19 am Adding width to the tyres wont change speedometer readings as you aren't increasing the circumference. If you put 225/50/18's on the front then you would affect the speedo.
The 225/40s do have a bigger circumference as the height value of a tyre (40) is a % of the tyre width

40% of 225 is more than 40% of 215
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Re: 215-40-18 or 225-40-18 tyres on Polo GTI

Post by SRGTD »

Are forum members who are UK based and who are changing - or have already changed - their tyres from 215/40 R18 to 225/40 R18 informing their insurers? In the UK, pretty much all insurers will have a requirement in the policy booklet to inform them of any modification to the vehicle. Most insurers will consider a modification to be any change to the spec of the car as it left the factory, so using this definition of a modification, changing tyre size would be a modification.

IMO it’s unlikely that an insurer would refuse to continue providing cover on a car or change the premium because the tyres were changed from 215/40 R18 to 225/40 R18 as the difference is small. It could also be argued that changing from rock hard Bridgestones to grippier Michelin’s improve the car’s handling so makes it safer and therefor improves the insurance risk. However, if there is a requirement in the policy to inform the insurer and this hasn’t been complied with, then technically the insurer could try to void the policy in the event of a claim. Whether or not they’d be successful in doing this (unlikely I’d have thought), who knows, but I wouldn’t be giving an insurer any excuse to try and void my policy!

Interested to hear the views of any UK forum member who’s made this change or are considering making it. Apologies to forum members who’re outside the UK - not meaning to exclude you, but the insurance requirements in relation to modifications may be different to the UK position.
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Re: 215-40-18 or 225-40-18 tyres on Polo GTI

Post by fazzy »

PhilArnold wrote: Sat Jun 13, 2020 4:15 am
stuartrendall wrote: Sat Jun 13, 2020 12:19 am Adding width to the tyres wont change speedometer readings as you aren't increasing the circumference. If you put 225/50/18's on the front then you would affect the speedo.
The 225/40s do have a bigger circumference as the height value of a tyre (40) is a % of the tyre width

40% of 225 is more than 40% of 215
Thank you 😊 saved me a lot of writing.
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Re: 215-40-18 or 225-40-18 tyres on Polo GTI

Post by monkeyhanger »

PhilArnold wrote: Sat Jun 13, 2020 4:15 am
stuartrendall wrote: Sat Jun 13, 2020 12:19 am Adding width to the tyres wont change speedometer readings as you aren't increasing the circumference. If you put 225/50/18's on the front then you would affect the speedo.
The 225/40s do have a bigger circumference as the height value of a tyre (40) is a % of the tyre width

40% of 225 is more than 40% of 215
The change is tiny, and of no concern. I wrote a lengthy post on this a while back (maybe in this very thread). The overall wheel circumference increases 8mm, about 1.4% if I remember rightly. The circumference of any given tyre is goinv to change by 10-13mm from new to legal minimum tread depth (1.6mm in the UK).
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Re: 215-40-18 or 225-40-18 tyres on Polo GTI

Post by PhilArnold »

monkeyhanger wrote: Sat Jun 13, 2020 9:55 am
PhilArnold wrote: Sat Jun 13, 2020 4:15 am
stuartrendall wrote: Sat Jun 13, 2020 12:19 am Adding width to the tyres wont change speedometer readings as you aren't increasing the circumference. If you put 225/50/18's on the front then you would affect the speedo.
The 225/40s do have a bigger circumference as the height value of a tyre (40) is a % of the tyre width

40% of 225 is more than 40% of 215
The change is tiny, and of no concern. I wrote a lengthy post on this a while back (maybe in this very thread). The overall wheel circumference increases 8mm, about 1.4% if I remember rightly. The circumference of any given tyre is goinv to change by 10-13mm from new to legal minimum tread depth (1.6mm in the UK).
oh yeah I completely agree with you, miniscule change but was just pointing out how the tyre sizing numbers work
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Re: 215-40-18 or 225-40-18 tyres on Polo GTI

Post by monkeyhanger »

SRGTD wrote: Sat Jun 13, 2020 8:53 am Are forum members who are UK based and who are changing - or have already changed - their tyres from 215/40 R18 to 225/40 R18 informing their insurers? In the UK, pretty much all insurers will have a requirement in the policy booklet to inform them of any modification to the vehicle. Most insurers will consider a modification to be any change to the spec of the car as it left the factory, so using this definition of a modification, changing tyre size would be a modification.

IMO it’s unlikely that an insurer would refuse to continue providing cover on a car or change the premium because the tyres were changed from 215/40 R18 to 225/40 R18 as the difference is small. It could also be argued that changing from rock hard Bridgestones to grippier Michelin’s improve the car’s handling so makes it safer and therefor improves the insurance risk. However, if there is a requirement in the policy to inform the insurer and this hasn’t been complied with, then technically the insurer could try to void the policy in the event of a claim. Whether or not they’d be successful in doing this (unlikely I’d have thought), who knows, but I wouldn’t be giving an insurer any excuse to try and void my policy!

Interested to hear the views of any UK forum member who’s made this change or are considering making it. Apologies to forum members who’re outside the UK - not meaning to exclude you, but the insurance requirements in relation to modifications may be different to the UK position.
There's no chance you would get a claim rejected for doing this.

No-one could successfully argue on an indurers behalf that increasing the amount of rubber in contact with the road by 5% would or could adversely affect the safety of the car. It does not increase the official performance, nor have the potential to make the car more attractive to thieves. The car is safer with more tyre touching the road (tyre properties of a particular tyre are subjective and no insurer stipulates what brands you.can or can't fit).

225/40/R18 is a legitimate and mainstream tyre choice for a 7.5J width 18" wheel. Golfs/Passats/Arteons and Jettas all use 225/40/R18 tyres with 7.5J 18" wheels.

Tyre stretching (fitting unsuitable width tyres onto wheels) is a whole different ball game - that is highly questionable and would rightly be a point of contention for a insurer if you had a blow-out that caused a crash.

VW's decision to fit 215/40/R18 rather than 225/40/R18 is either a supplier incentive or emissions led decision - insurers care about safety, performance enhancement and desirability to thrives, not whether VW are trying to scrape 2g CO2/km off their official figures.

I asked a friend of a friend who's pretty high up in Aviva (and on a ludicrous wage - his annual bonus is higher than my wage!) about this and he laughed at the idea it was a notifiable modification. Tyres fitted by VW are a commercial decision and the suitability of certain tyre sizes to certain wheel sizes is robustly established.

215/40/R18 is such a niche tyre size that no tyre place has them on the shelf as stock (not even Costco - and they stock a lot of tyres), you have to order them in. If you have a puncturehalfway through a long journey and limp to the local tyre fitter, are you going to wait 2 or 3 days for a 215/40/R18 to come onto stock or buy a pair of 225/40/R18s? That space saver is only good for 120 miles because they're soft rubber and only have 2mm/2.5mm tread.

If insurers cared that much about tyre choice, they'd be offering a discount to ditch Bridgestones due to their woeful wet and dry grip.
Last edited by monkeyhanger on Sat Jun 13, 2020 10:23 am, edited 1 time in total.
SRGTD
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Re: 215-40-18 or 225-40-18 tyres on Polo GTI

Post by SRGTD »

monkeyhanger wrote: Sat Jun 13, 2020 10:17 am
SRGTD wrote: Sat Jun 13, 2020 8:53 am Are forum members who are UK based and who are changing - or have already changed - their tyres from 215/40 R18 to 225/40 R18 informing their insurers? In the UK, pretty much all insurers will have a requirement in the policy booklet to inform them of any modification to the vehicle. Most insurers will consider a modification to be any change to the spec of the car as it left the factory, so using this definition of a modification, changing tyre size would be a modification.

IMO it’s unlikely that an insurer would refuse to continue providing cover on a car or change the premium because the tyres were changed from 215/40 R18 to 225/40 R18 as the difference is small. It could also be argued that changing from rock hard Bridgestones to grippier Michelin’s improve the car’s handling so makes it safer and therefor improves the insurance risk. However, if there is a requirement in the policy to inform the insurer and this hasn’t been complied with, then technically the insurer could try to void the policy in the event of a claim. Whether or not they’d be successful in doing this (unlikely I’d have thought), who knows, but I wouldn’t be giving an insurer any excuse to try and void my policy!

Interested to hear the views of any UK forum member who’s made this change or are considering making it. Apologies to forum members who’re outside the UK - not meaning to exclude you, but the insurance requirements in relation to modifications may be different to the UK position.
There's no chance you would get a claim rejected for doing this.

No-one could successfully argue on an indurers behalf that increasing the amount of rubber in contact with the road by 5% would or could adversely affect the safety of the car. It does not increase the official performance, nor have the potential to make the car more attractive to thieves. The car is safer with more tyre touching the road (tyre properties of a particular tyre are subjective and no insurer stipulates what brands you.can or can't fit).

225/40/R18 is a legitimate and mainstream tyre choice for a 7.5J width 18" wheel. Golfs/Passats/Arteons and Jettas all use 225/40/R18 tyres with 7.5J 18" wheels.

Tyre stretching (fitting unsuitable width tyres onto wheels) is a whole different ball game - that is highly questionable and would rightly be a point of contention for a insurer if you had a blow-out that caused a crash.

VW's decision to fit 215/40/R18 rather than 225/40/R18 is either a supplier incentive or emissions led decision - insurers care about safety, performance enhancement and desirability to thrives, not whether VW are trying to scrape 2g CO2/km off their official figures.

I asked a friend of a friend who's pretty high up in Aviva (and on a ludicrous wage - his annual bonus is higher than my wage!) about this and he laughed at the idea it was a notifiable modification. Tyres fitted by VW are a commercial decision and the suitability of certain tyre sizes to certain wheel sizes is robustly established.

If insurers cared that much about tyre choice, they'd be offering a discount to ditch Bridgestones due to their woeful wet and dry grip.
So that’s a ‘no’ then to my original question.
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Re: 215-40-18 or 225-40-18 tyres on Polo GTI

Post by monkeyhanger »

^ if it helps you sleep better at night, by all means tell them, but chances are you'll get a call centre employee who's first language isn't the same as yours, who misunderstands your notification, logs you're changing your wheels for aftermarket ones and applies a premium increase on that basis, :D
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