Friday, 13 October 2017

Choosing The Best Tyres For My S5 Sportback

When I bought the car, the front tyres were one of the things I knew I'd need to replace within the first year, shortly followed by the rears. I hadn't thought too much about which tyre I'd be fitting as I assumed I could fit my go-to tyre, Goodyear Eagle F1 Asymmetric 2's or 3's, after such a positive experience of them on my BMW E46 330d and E92 335i.

Sadly though, Goodyear don't currently produce the Eagle F1's in the right size, 265/30, to fit the Audi's 20" 7-arm double-spoke alloys.

The car is currently shod with Dunlop SportMaxx GTs, which perform ok in terms of grip (both in the wet and dry) but suffer from fairly alarming tram-lining.


To get an idea of what's available, I always head over to camskill.co.uk. A quick browse yielded the following short list:

AttributeDunlop
SportMaxx GT
265/30 R20
94Y XL MFS TL
Vredestein
Ultrac Vorti
265/30 R20
94Y XL TL
Hankook
Ventus S1 Evo 2 K117
265/30 R20
94Y XL TL
Michelin
Pilot Sport 4S
265/30 R20
94Y XL TL
Cost (/tyre)*£178.70£163.80£171.60£232.30
EU - Fuel EfficiencyEECE
EU - Wet GripBBAA
EU - Noise Class1122
EU - Noise dB68707371
EU - CategoryC1C1C1C1
*camskill.co.uk prices as of 05/10/2017

I've all but ruled out refitting the Dunlop's, so it's down to three.

My idea of 'best' is a good all round tyre, competitive dry and wet grip, quiet, good longevity and doesn't break the bank.


Wet Grip


Let's start by looking at the most important job of the tyre, sticking the car to the road.


The following is an extract from mytyres.co.uk explaining the EU Tyre Label rating system.
The tyre label is classified according to classes "A" to "G", whereby "D" and "G" are not used. The braking distance difference from one class to the next on a wet road at an initial speed of 80 km/h (50mph) between 1 and 2 vehicle lengths (3.0 - 6.0 m), is on average around 4.5 m. Between class "G" and class "A" there is a total reduction of approx. 30% in the braking distance.
In total the braking difference between, for example, Class "A" and "F" is over 18 metres.
ClassCar tyre
index value (G)
- A -≥ 1,55
- B -1,40 - 1,54
- C -1,25 - 1,39
- D --
- E -1,1 - 1,24
- F -≤ 1,09
- G --
Boundary values for classification of wet grip

All three tyres have got good grip, it'd be nice to have the A rating, but a maximum difference of one car length isn't the be all and end all.

Besides, I'm happy enough with the grip provided by the Dunlops which rate the same as the Vredesteins.


Fuel Efficiency


Next up, fuel efficiency rating. Any saving here would be lovely, *cough 23mpg avg*.
The evaluation is given in classes "A" to "G", whereby "D" is not used. Improvement by one class signifies a saving of approx. 0.1 litre of fuel over 100 km (62.14 miles). Between class "G" and class "A" there is a total reduction of approx. 7.5% of the fuel consumption.
ClassCar tyre running friction
(CR) in kg/t
- A -≤ 6,5
- B -6,6 - 7,7
- C -7,8 - 9,0
- D --
- E -9,1 - 10,5
- F -10,6 - 12,0
- G -≥ 12,1
Boundary values for classification of running friction


All good information, but difficult to associate with, here's what that actually means in terms of money in your pocket.

At the time of writing, Shell V Power in my area is selling at £1.289 per litre, so the saving per 100km by fitting the Hankook's over the others is £0.13. I do about 24,000km (15,000 miles) a year which means, if the label rating is to be believed, a maximum theoretical saving of £30.94 per year, better than nowt.

So far it's two for two in favour of the Hankooks, however, it all comes unstuck when you look at the noise rating.


Noise dB


Noise is complicated to say the least, for starters the dB scale is not linear, it's logarithmic. For example an increase of 3dB is barely perceivable by the human ear, however, an increase of 10dB is perceived as 2x the loudness.

An increase of 5dB, e.g. going from the Dunlops at 68dB to the Hankooks at 73dB, would be a significant increase in noise. Not ideal considering the tyre roar from the 20" wheels is already quite loud.

On the other hand, the 2dB increase from the Dunlops to Vredesteins would barely, if at all, be perceivable.

The Vredesteins outshine both the Michelins and the Hankooks here.


Automotive Press Reviews


Auto Bild, the German equivalent of AutoCar and What Car? perform a number of tyre tests throughout the year. Their latest test of ultra high performance (UHP) tyres has been summarised by tyrereviews.co.uk. All three of the tyres I've selected are present in this test.

Auto Bild test each of the following attributes; wet/dry handling, wet/dry braking, rolling resistance and noise. The overall winner of their test was the Michelin Pilot Sport 4, closely followed by the Vredestein Ultrac Vorti in joint 2nd alongside my go-to the Goodyear Eagle F1 Asymmetric 3's and finally the Hankook Ventus S1 evo2 down in joint 4th.

Although the Michelin Pilot Sports came in top, the Vredesteins out performed them in several tests, including wet braking, dry braking and noise. Where the Michelins came out top, the Vredesteins were right behind them, only 0.1mph behind in the wet handling test for example.

In stark contrast to the EU Label, Auto Bild rated the Hankook the quietest tyre in the test, closely followed by the Vredesteins.


Customer Reviews


Finally then, on to actual customer reviews. The best site I've found for this is again, tyrereviews.co.uk, you can search for your specific vehicle and see the ratings and comments made against the tyres that owners of your car have actually used.

For the Audi S5, here's the rating summary.


It shows the Vredestein Ultrac Vorti firmly in top spot. Here's one of the reviews for the Vredesteins:
Originally my Audi S5 came with Dunlop Sport Maxx, and they where "ok", but always felt bumpy on bad roads, and noisy also.  
Now I got 4 Vredestein Ultrac Vorti, and the difference is huge:
- much more stickyness, less bumpy
- very good feedback, especially in corners
- much less noise
- sporty and comfortable in one tyre
- very good when wet (no aquaplanning)


Conclusion


That pretty much seals the deal for me, according to the EU label the Hankooks perform well in the wet, have good fuel efficiency properties and are competitively priced, but in Auto Bild's real world testing they didn't live up to those ratings.

The Michelins may have the edge on wet handling, but they are louder, provide little fuel efficiency benefit and cost a whopping £68.50 more PER TYRE?!

I'll be putting my money where my mouth is and fitting the Vredestein Ultrac Vortis, stay tuned for my full review to find out whether they are the best all round tyre for the Audi S5 Sportback.


Let me know what you think in the comments, have you fitted any of the above tyres? Happy with them or wish you'd gone for a different choice?

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Monday, 2 October 2017

What Does The T In V6T Stand For?

Chances are if you own, or have looked at buying, an Audi with the V6T badge you'll have questioned what the T stands for.

On top of that, you'll have definitely had someone look at you gone out when you tell them your car's supercharged not turbocharged. 

The V6T badge is probably one of the most confusing badges ever to grace the body panels of an Audi - if you ignore their new power based numbering system that is...

So what the heck does it mean?


Let's start with what it doesn't mean. It definitely can't stand for turbo for obvious reasons, despite that it actually does stand for turbo in TFSI. Here's the quote direct from Audi's glossary website:

"Turbo fuel stratified injection or TFSI combines petrol direct injection with turbocharging."

Clear as mud right?

Logically, you might think the T is some German word for supercharger, but as we know from 00's Mercedes, the German word for supercharger is kompressor.

Although wrong, the following 'fact' did make me chuckle, probably more than it should have. It's believed that the guy who designed the V6T logo had a lisp, and actually the T stands for Thupercharged.


A more sensible, yet tenuous link, might be that the T stands for TVS Supercharger, or Twin Vortices Series Supercharger in full.

In reality, the T stands for forced induction, be that turbocharging or supercharging. A bit of a cop out on Audi's part in my opinion. 

If you had a blank canvas, you'd probably come up with V6S or 3.0S right? Well, the designers (being designers) wanted the only S on the car to be that of S in the S4 / S5 badge.

Audi S5 Sportback Meteor Grey boot lid trunk badge

As someone who works in the automotive industry I can wholly believe this impasse went on and on, until a decision was made at the expense of the customer rather than the ego of a senior manager.

In the end they went with the T as it was 'familiar' to the customer, having been used in the 1.8T and 2.0T badges.

Fortunately, if the V6T badge really bugs you, there was a supercharged badge produced for the later face-lifted B8.5 S4 and S5 as an option. It was available with a carbon fibre insert or plain red insert to match the S4/5 badge, part numbers: 4F0853601 and 4F08536012AZZ respectively.


I believe you can still get these from the dealers, if not you can also pick them up from ECS Tuning, which is where I've pinched the images above from. Watch out for cheap copies on eBay and Amazon though, they are significantly lower quality.

Let me know what you think in the comments below, have you removed / replaced your badge? Do you actually prefer the V6T to the Supercharged badge?

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