Tyre Aspect Ratio

[AusieOccy]

Hi Fellow Octavians,

 

I have a VRS wiith 225/40/18 tyres (40 being the aspect ratio).  My current tyres aren't the quieteset and I have been looking online to see what tyres have the least noise.  I came up with Michelin Primacy 3 ST's (reviews are really good).  The only problem is that they only come in 225/45/18 here in AU.  This means that the tryre is a bit higher which no doubt would effect the speedo reading.

 

Does anyone know what else this may effect.  I have read a few posts on other forums that it will wreck your diff and transmission (personnally I can't see how).  Also going from 40's to 45's how much of a speed difference will show on the speedo and can you adjust this with VCDS.

[Gadget007]

a rough calculation results in about 3km/hr error at 100km/hr, that is if your speedo is correct with original tyres, the 45 series ones will have the car doing 103km/hr at indicated 100km/hr.

 

(good to see a fellow Aussie on here)

[flybynite]

Lots of good online calculators that let you play with the numbers

 

http://www.willtheyfit.com

 

Is a good one

[Ootohere]

Do not assume because the Profile Numbers make it look like you will have taller sidewalls that you will.

Compare Tyres side by side, because Brand & Tread can mean say that the Tyre is Wider with Rim Protection then tread 

and as an example i have Pirelli Zero Nero 205/40 R17 that are physically bigger than Dunlop 205/40 R 17 

but also bigger than Hyfly 215/40 R 17 that i have on now.

 

http://kouki.co.uk/utilities/visual-tyre-size-calculator

 

As to different size tyres on different axles, that can affect certain types of AWD / 4x4 / Part Time All Wheel drive vehicles

Diff / Transmission / VCU etc

Not Front or Rear Wheel Drive with Matching Pairs of tyre on the different axles.

Many vehicles run different Hight & Widths of tyres front and rear.

(it is you vehicle the matters obviously, not others so be sure what you are doing.)

 

So basically check side by side what you are putting on,

and some bigger tyres might make your Speedo / Mileometer more accurate and not have it over reading by as much as it 

does with OEM tyres, and still not under reading.

[vegit8]

 

As to different size tyres on different axles, that can affect certain types of AWD / 4x4 / Part Time All Wheel drive vehicles

Diff / Transmission / VCU etc

Not Front or Rear Wheel Drive with Matching Pairs of tyre on the different axles.

...

A friend of mine had the centre diff completely fail on a German autobahn on his way back from a skiing holiday.

The reason why?

Before leaving he had fitted 2 new winters to the front axle but left the old ones on the back.

The transmission "wind up" caused the failure... £7000 repair bill - including transport back from Germany to the UK.

Good job it was a Hyundai 7 year warranty.

[Ootohere]

The Hyundai / Volvo / Land Rover or any other Manufacturers warranty usually does not cover you were the Manufacturers Guidelines and Warnings are ignored.

 

But it has been happening for years now, even just with a New pair of Tyres fitted & old ones on the other axle.

and even with one spare going on for a limited amount of time.

It is why Owners / Drivers should read the Owners Manual, and Technicians and tyre fitters should know their job and vehicles.

(it is why a carry 2 matching spares when travelling in a 4x4.)

[EoinM]

If you want quiet tyres Goodyear Efficient Grip Performance are the best I've come across in a long time. Swapped my factory contis for them and they transformed the car.

[fatzy]

Hi Fellow Octavians,

 

I have a VRS wiith 225/40/18 tyres (40 being the aspect ratio).  My current tyres aren't the quieteset and I have been looking online to see what tyres have the least noise.  I came up with Michelin Primacy 3 ST's (reviews are really good).  The only problem is that they only come in 225/45/18 here in AU.  This means that the tryre is a bit higher which no doubt would effect the speedo reading.

 

Does anyone know what else this may effect.  I have read a few posts on other forums that it will wreck your diff and transmission (personnally I can't see how).  Also going from 40's to 45's how much of a speed difference will show on the speedo and can you adjust this with VCDS.

As long as all 4 tyres are changed and all have the same rolling circumference, you won't get any problems with diff or transmission (even if you had a 4-wheel driven car). If you switch from 40 to 45 profile, the rolling circumfere will increase with about 3-4%. Your speedo will show the speed closer to actual speed. This is witin legal variations in my country.

There are no way to recalibrate the speedo, and it makes no sence either with such a small deviation.

I don't think you should worry about variations within the same dimension, all should be within standardized norms.

[flybynite]

As I think a few have said before there wont be much of an issue practically as it is only a few percent.

 

It is worth thinking about the fact that you will be deviating from the list of approved tyre sizes for that model, as I don't think 225/45/18 is on that list. Whether that is a problem depends on country regs, insurance and how much risk you are prepared to take but it is just something to keep in mind as smaller things have caused bigger problems.

 

Most models

 

195/65 R15 91H 6J x 15 

195/65 R15 91H 6J x 15 

205/55 R16 91H 6.5J x 16 

205/55 R16 91H 6J x 16 

205/55 R16 91H 6J x 16 

225/45 R17 91H 7J x 17 

205/50 R17 89H 6J x 17 

205/50 R17 89H 6J x 17 

225/40 R18 92Y 7.5J x 18 

 

VRS

205/50 R17 89V 6J x 17 

205/50 R17 89V 6J x 17 

225/45 R17 91V 7.5J x 17 

225/40 R18 92Y 7.5J x 18 

225/35 R19 88Y 7.5J x 19

 

The full list is in the Wheels and Tyres bit of the manuals downloadable in one of the thread stickies or on ETKA

[cortina63]

The 40 or 45,is the percentage of the width of the tyre, 225/40, means a sidewall depth of 40% of 225,sidewall depth on a 17" wheel is bigger than on an 18" wheel, in order to keep the rolling circumference the same, and in turn the accuracy of the speedo

[AusieOccy]

Thanks All,  after reading all the replies I think it looks like it will be ok with 45s.  I dont have AWD and am planning on changing all 4 tyres (when the old ones wear out).  My speedo is currently out by 3PKH at 100K so it will just get more accurate.

[brad1.8T]

Hi Fellow Octavians,

 

I have a VRS wiith 225/40/18 tyres (40 being the aspect ratio).  My current tyres aren't the quieteset and I have been looking online to see what tyres have the least noise.  I came up with Michelin Primacy 3 ST's (reviews are really good).  The only problem is that they only come in 225/45/18 here in AU.  This means that the tryre is a bit higher which no doubt would effect the speedo reading.

 

Does anyone know what else this may effect.  I have read a few posts on other forums that it will wreck your diff and transmission (personnally I can't see how).  Also going from 40's to 45's how much of a speed difference will show on the speedo and can you adjust this with VCDS.

It won't wreck your diff or gearbox.

 

225/45r18 will make the speedo pretty much 100 speedo=101 actual so you'll need to be careful. I've driven the last 30,000km on 100=100 and didn't find it hard to maintain an accurate speed.  I've just gone back to 100=96 and it's a pain - I find I am actually speeding more. They are also an uncommon size so you'll be paying $350-$400 ?

 

You might also consider 235/40r18 which aren't quite as tall and should give 100=98.  They are a Falcadore size so generally much cheaper ($160 - $240).  

 

Have you considered Conti maxContact5, goodyear F1 Assymetric 2, Michelin PS3, Yokohama Advan dB Decibel V551, Toyo Teo Plus or the Goodyear Eagle Efficient Grip?  They are all reasonably quiet -especially the Yokohama and the Toyo.  Any "quiet tyre" is generally a small block tread so it's likely you will take a performance hit no matter what brand you choose.

 

Unfortunately you haven't said what you are running at the moment, so it's hard to compare.

 

The Octy2 is really fussy about alignment, so you need your aligner to set it up with non-aggressive settings so it isn't too noisy.

 

They have also skimped on sound deadening, so you might be better to channel some money in that direction.

Edited 17 July, 2015 by brad1.8T

[AusieOccy]

It won't wreck your diff or gearbox.

 

225/45r18 will make the speedo pretty much 100 speedo=101 actual so you'll need to be careful. I've driven the last 30,000km on 100=100 and didn't find it hard to maintain an accurate speed.  I've just gone back to 100=96 and it's a pain - I find I am actually speeding more. They are also an uncommon size so you'll be paying $350-$400 ?

 

You might also consider 235/40r18 which aren't quite as tall and should give 100=98.  They are a Falcadore size so generally much cheaper ($160 - $240).  

 

Have you considered Conti maxContact5, goodyear F1 Assymetric 2, Michelin PS3, Yokohama Advan dB Decibel V551, Toyo Teo Plus or the Goodyear Eagle Efficient Grip?  They are all reasonably quiet -especially the Yokohama and the Toyo.  Any "quiet tyre" is generally a small block tread so it's likely you will take a performance hit no matter what brand you choose.

 

Unfortunately you haven't said what you are running at the moment, so it's hard to compare.

 

The Octy2 is really fussy about alignment, so you need your aligner to set it up with non-aggressive settings so it isn't too noisy.

 

They have also skimped on sound deadening, so you might be better to channel some money in that direction.

I have read that the Yokohama & Toyo do not last as long as the Michelins.  I will have a look at the Goodyears as they also have some good reviews.  My cuttent tyres are Bridgestone Potenzas.  These are made more for speed than comfort.  I have had my fun with the VRS, now its time for some comfort.

[brad1.8T]

I have read that the Yokohama & Toyo do not last as long as the Michelins.  I will have a look at the Goodyears as they also have some good reviews.  My cuttent tyres are Bridgestone Potenzas.  These are made more for speed than comfort.  I have had my fun with the VRS, now its time for some comfort.

As a die-hard Michelin fanboi, I'll confirm that Michelin generally give excellent mileage.

 

Assuming you have Potenza RE050A - they only have a Tread wear rating of 140 and they are noisy on the Octavia.

 

Michelins PS3 are around 280 TWR & the Primacy are around 320 IIRC.  The Primacy won't perform as well as the PS3 though.

 

The Toyo Teo is around 300 TWR

 

Yokohama is said to be 600 but i doubt that - probably around the 300 mark too.

 

They'll all last longer than the RE050A but if it was my car I'd fit 235/40r18 Michelin PS3.  They are a great all-rounder.  I had the Primacy HP on the car for 70,000km.  Good tyre but slightly lacking in some aspects.

[kfckfc]

+1 on what Brad1.8T has said.

 

Michelin are generally more expensive but have very good balance of grip/wear and also quiet. I currently have Primacy HP but am likely to go for Pilot Sport 3 or the Good Year Eagle F1 AS2 when I change.

 

I personally would not recommend the RE050A as I found them to wear too quickily and grip was not reflective of the price or wear rate (although that was on a MR2 Roadster not an O3)

[brad1.8T]

Michelin are generally more expensive but have very good balance of grip/wear and also quiet. I currently have Primacy HP but am likely to go for Pilot Sport 3 or the Good Year Eagle F1 AS2 when I change.

 

I personally would not recommend the RE050A as I found them to wear too quickily and grip was not reflective of the price or wear rate (although that was on a MR2 Roadster not an O3)

 

To be fair to the RE050A, they are now a really old tyre design - they've been on the market 10+ years and tyre technology has progressed since they were released.  In the past few years they have halved in priced (in AUS) and aren't a bad buy for what they are.  My last set managed 30,000km with some judicious X-rotation and were good for at least another 5k-10k but the guy that does my registration checks is a bit strict so I had to bin them.  I'm now onto a 2nd set because people keep offering me near new sets of wheels & tyres for crazy cheap prices otherwise I'd be back onto Michelin again.