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

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fran_92
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215-40-18 or 225-40-18 tyres on Polo GTI

Post by fran_92 »

Hi everyone,

I have seen some messages in different posts about this topic, but any specific post about this question. All the people that we have a Polo GTI with Brescias have 215/40/18 tyres. This tyre measure is more expensive than 225/40/18. Brescias can support this tyre measure, but there are some doubts in the air, and this post is to discuss these doubts.

If we replace our tyres with 225/40/18 tyres instead of 215/40/18, our car is going to be 4mm upper, the tyre diameter is going to be 8mm more and we are going to have 1cm more of width. Like the tyre diameter is bigger, my doubts are:

- the speedometer is going to mark correctly the speed?
- what pressures are the correct ones?
- Tyre pressure loss indicator is going to work properly?
- If anyone has these tyre measure, can you upload some picture to see how they fit?

Thank you!!
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OomStu_ZA
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Re: 215-40-18 or 225-40-18 tyres on Polo GTI

Post by OomStu_ZA »

Found a website that offers some technical explination in the images below:
Capture2.JPG
Capture1.JPG
- the speedometer is going to mark correctly the speed?
[from what I've read there will be an approx. 1.4% difference in reading, so not really that noticeable]
- what pressures are the correct ones?
[no idea but guess same as owners manual recommends]
- Tyre pressure loss indicator is going to work properly?
[I doubt there will be a problem with the device/sensor]
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Re: 215-40-18 or 225-40-18 tyres on Polo GTI

Post by monkeyhanger »

fran_92 wrote: Mon Mar 30, 2020 10:48 am Hi everyone,

I have seen some messages in different posts about this topic, but any specific post about this question. All the people that we have a Polo GTI with Brescias have 215/40/18 tyres. This tyre measure is more expensive than 225/40/18. Brescias can support this tyre measure, but there are some doubts in the air, and this post is to discuss these doubts.

If we replace our tyres with 225/40/18 tyres instead of 215/40/18, our car is going to be 4mm upper, the tyre diameter is going to be 8mm more and we are going to have 1cm more of width. Like the tyre diameter is bigger, my doubts are:

- the speedometer is going to mark correctly the speed?
- what pressures are the correct ones?
- Tyre pressure loss indicator is going to work properly?
- If anyone has these tyre measure, can you upload some picture to see how they fit?

Thank you!!
This has been discussed at length previously. 225/40 R18 is the standard tyre on the 18" wheels of the Golf GTI/GTD/R. The standard wheels on those models are 7.5J wide, same as Polo GTI's Brescia. Perfect fit.

The rolling circumference of the wheel will increase by 8mm as you say, but this results in an increase of approximately 1.27%, contributing to 1mph under-read on your speedo at 70mph. As the speedo over-reads by about 3% vs GPS anyway and there is an allowable tolerance of (can't 100% remember) something like 2.5% then we're fine. The difference in rolling diameter between new and fully worn 215/40 R18 is about 12mm - to put your 8mm into context!

215/40 R18 are so expensive at retail as it is such a niche size, 225/40 R18 are much more common - economies of scale and all that. Why pay £140 for a 215 tyre when you can pay £80 for a 225?

VW's choices will have been determined by either what they can get cheap in the volumes they deal with, or marginally reduced CO2 rating for the car.

Wider tyres, lower air pressure required to support same load. I'd recommend 36psi fronts, 32psi rears for best ride without compromising wear or fuel economy. Go higher than that and you feel the ride is harder but mpg doesn't get any better.

The PS4s have a generous protective lip - you'd have to seriously clout your wheel against the kerb to scrape it.
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fran_92
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Re: 215-40-18 or 225-40-18 tyres on Polo GTI

Post by fran_92 »

monkeyhanger wrote: Mon Mar 30, 2020 1:00 pm
fran_92 wrote: Mon Mar 30, 2020 10:48 am Hi everyone,

I have seen some messages in different posts about this topic, but any specific post about this question. All the people that we have a Polo GTI with Brescias have 215/40/18 tyres. This tyre measure is more expensive than 225/40/18. Brescias can support this tyre measure, but there are some doubts in the air, and this post is to discuss these doubts.

If we replace our tyres with 225/40/18 tyres instead of 215/40/18, our car is going to be 4mm upper, the tyre diameter is going to be 8mm more and we are going to have 1cm more of width. Like the tyre diameter is bigger, my doubts are:

- the speedometer is going to mark correctly the speed?
- what pressures are the correct ones?
- Tyre pressure loss indicator is going to work properly?
- If anyone has these tyre measure, can you upload some picture to see how they fit?

Thank you!!
This has been discussed at length previously. 225/40 R18 is the standard tyre on the 18" wheels of the Golf GTI/GTD/R. The standard wheels on those models are 7.5J wide, same as Polo GTI's Brescia. Perfect fit.

The rolling circumference of the wheel will increase by 8mm as you say, but this results in an increase of approximately 1.27%, contributing to 1mph under-read on your speedo at 70mph. As the speedo over-reads by about 3% vs GPS anyway and there is an allowable tolerance of (can't 100% remember) something like 2.5% then we're fine. The difference in rolling diameter between new and fully worn 215/40 R18 is about 12mm - to put your 8mm into context!

215/40 R18 are so expensive at retail as it is such a niche size, 225/40 R18 are much more common - economies of scale and all that. Why pay £140 for a 215 tyre when you can pay £80 for a 225?

VW's choices will have been determined by either what they can get cheap in the volumes they deal with, or marginally reduced CO2 rating for the car.

Wider tyres, lower air pressure required to support same load. I'd recommend 36psi fronts, 32psi rears for best ride without compromising wear or fuel economy. Go higher than that and you feel the ride is harder but mpg doesn't get any better.

The PS4s have a generous protective lip - you'd have to seriously clout your wheel against the kerb to scrape it.
Hi, thanks for your answer. I know that you have discussed about it, but I haven't found an explicit post about this topic, and I think that it would be interesting to write all the experiences :)

Have you some picture of your car with these tyres? It just 4mm, but to see how the car looks like with them

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

Post by monkeyhanger »

My car is filthy at the moment (and I'm a key worker, so no time to wash it), so excuse the muck.
I'll take a pic later when I'm finished work, but you honestly won't see a difference with a wheel that has 1.27% more diameter than standard. A pic will help you appreciate the protective lip as being very generous, but I know I've put pics up for that already.

Not sure what you mean by explicit unless you want a certified endorsement from a car expert like Chris Harris or some VW GmbH Head of Engineering type guru.

My car has been serviced with the PS4s in place and the VW tech was not bothered when I discussed the reasons for change. I'd have had the 215s if they weren't 60% more expensive, or if there was even a remotely relevant reason not to. They're an ideal fit for the wheel type (as previously demonstrated by Golf fitment), no clearance/snagging issues. There is no reason not to do this. No insurance implications (I checked) because there are no engineering/safety reasons not to.

One thing I might do in your shoes... next time I replace the tyres, I'll get PSS rather than PS4, they're even better, for a fiver a corner more at Costco, but they are a special order rather than stock.
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Re: 215-40-18 or 225-40-18 tyres on Polo GTI

Post by Ima »

Thanks monkey hanger that’s great as there is such a price difference. I saw in earlier threads that you initially thought that the polo gti might on the 225 tyres might touch rear arch or need spacers something it sounds like not of that is an issue now you’ve tried them. If mine ever gets here in the covid lockdown I’ll look at the same.
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Re: 215-40-18 or 225-40-18 tyres on Polo GTI

Post by S_94 »

Got some pictures at hand if that helps. :)

I bought the PS4's on monkeyhanger's recommendation. Would recommend anyone else do the same, they have improved the car ten fold. And having the protective lip is a benefit!
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Re: 215-40-18 or 225-40-18 tyres on Polo GTI

Post by monkeyhanger »

Ima wrote: Mon Mar 30, 2020 1:59 pm Thanks monkey hanger that’s great as there is such a price difference. I saw in earlier threads that you initially thought that the polo gti might on the 225 tyres might touch rear arch or need spacers something it sounds like not of that is an issue now you’ve tried them. If mine ever gets here in the covid lockdown I’ll look at the same.
My worries about the wheels catching the wheel lining were due to my rear right hand side rear wheel arch liner being fitted incorrectly at the factory - this made it flare out a lot. I fixed that and then there were no clearance worries.
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Re: 215-40-18 or 225-40-18 tyres on Polo GTI

Post by fran_92 »

monkeyhanger wrote: Mon Mar 30, 2020 1:53 pm My car is filthy at the moment (and I'm a key worker, so no time to wash it), so excuse the muck.
I'll take a pic later when I'm finished work, but you honestly won't see a difference with a wheel that has 1.27% more diameter than standard. A pic will help you appreciate the protective lip as being very generous, but I know I've put pics up for that already.

Not sure what you mean by explicit unless you want a certified endorsement from a car expert like Chris Harris or some VW GmbH Head of Engineering type guru.

My car has been serviced with the PS4s in place and the VW tech was not bothered when I discussed the reasons for change. I'd have had the 215s if they weren't 60% more expensive, or if there was even a remotely relevant reason not to. They're an ideal fit for the wheel type (as previously demonstrated by Golf fitment), no clearance/snagging issues. There is no reason not to do this. No insurance implications (I checked) because there are no engineering/safety reasons not to.

One thing I might do in your shoes... next time I replace the tyres, I'll get PSS rather than PS4, they're even better, for a fiver a corner more at Costco, but they are a special order rather than stock.
When I say explicit, I mean a unique post talking about this in this forum (sorry for my English). I have found some messages in different posts, but not one post discussing all this topic. Sorry if there is another post, if I had found it I would have not written another different.

Thanks for all the information
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Re: 215-40-18 or 225-40-18 tyres on Polo GTI

Post by fran_92 »

S_94 wrote: Mon Mar 30, 2020 2:28 pm Got some pictures at hand if that helps. :)

I bought the PS4's on monkeyhanger's recommendation. Would recommend anyone else do the same, they have improved the car ten fold. And having the protective lip is a benefit!
Thank you so much!!:)
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Re: 215-40-18 or 225-40-18 tyres on Polo GTI

Post by Ima »

Great pictures. The rim protection looks great. Price for 4 looking good too. Thanks for the advice .
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Re: 215-40-18 or 225-40-18 tyres on Polo GTI

Post by OomStu_ZA »

While this topic is active can anyone share what type of usage one can expect in Kilometers from the PS4? The factory Bridgestones on my car should last until ±40000/50000KM's depending on my drivning of course. If the Michelin's only offer say 30000KM's total (softer compund and all that) it may be better to stick with OEM from a milage standpoint.
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Re: 215-40-18 or 225-40-18 tyres on Polo GTI

Post by monkeyhanger »

OomStu_ZA wrote: Mon Mar 30, 2020 2:57 pm While this topic is active can anyone share what type of usage one can expect in Kilometers from the PS4? The factory Bridgestones on my car should last until ±40000/50000KM's depending on my drivning of course. If the Michelin's only offer say 30000KM's total (softer compund and all that) it may be better to stick with OEM from a milage standpoint.
I'll guarantee that the Bridgestones will last longer than the Michelins - they're rock hard, which is the underlying cause of their high levels of road noise and low levels of wet/dry grip and traction. I'd expect 18-20k miles on the fronts and 40k miles on the backs, or 30k miles all round if you rotate fronts to backs. My fronts have done 9k miles now - I'll check wear and report back.

Honestly though, this car is a far better car on grippier rubber. It performs better and your confidence in its abilities is hugely improved too. If the Michelins lasted half as long I'd still change. Leaving these on the car is like making Usain Bolt run in a pair of Dutch wooden clogs.
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Re: 215-40-18 or 225-40-18 tyres on Polo GTI

Post by Ima »

I wonder how pilot sport 4 compare to the Goodyear Asymetric 5. Goodyears work out nearly £70 cheaper but cheaper not always worth the cost saving.
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Re: 215-40-18 or 225-40-18 tyres on Polo GTI

Post by OomStu_ZA »

monkeyhanger wrote: Mon Mar 30, 2020 3:15 pm
OomStu_ZA wrote: Mon Mar 30, 2020 2:57 pm While this topic is active can anyone share what type of usage one can expect in Kilometers from the PS4? The factory Bridgestones on my car should last until ±40000/50000KM's depending on my drivning of course. If the Michelin's only offer say 30000KM's total (softer compund and all that) it may be better to stick with OEM from a milage standpoint.
I'll guarantee that the Bridgestones will last longer than the Michelins - they're rock hard, which is the underlying cause of their high levels of road noise and low levels of wet/dry grip and traction. I'd expect 18-20k miles on the fronts and 40k miles on the backs, or 30k miles all round if you rotate fronts to backs. My fronts have done 9k miles now - I'll check wear and report back.

Honestly though, this car is a far better car on grippier rubber. It performs better and your confidence in its abilities is hugely improved too. If the Michelins lasted half as long I'd still change. Leaving these on the car is like making Usain Bolt run in a pair of Dutch wooden clogs.
If only tyres were like shoes one could try before you buy :)

So if my calculation is correct sounds about the same as Bridgestones if 30000 Miles is equal to ± 480000 KM's using Google to convert.
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