That's because of the weights! The weight loss on the new MQB platform doesn't seem to have affected the sporty variants, ie. the VRS/GTI still weigh about as much as the old ones, while the regular cars are much lighter.

So the power to weight ratio of the 150 TDI is pretty close to the 184TDI.

Hadn't considered that but that's the reason. The only cars showing the real weigh loss are the ones that have reverted back to the lighter/simpler torsion beam rear suspension setup ie the 150tdi's

 

I am very very confused; has this got anything at all to do with whether or not VRS callipers now too big for 17" rims or was it just posted in the wrong place?

 

Pics of my new Winter 17s test fitted to my GTi with the same 340mm brakes as the VRS - half way down the post.  If buying 17s make sure they have the right 'et' and are quality light or normal weight rims (or OEM VAG rims with the right 'et') some far east made rims are thicker than normal and heavy (and some use softer alloys) and may not clear the calipers.

 

http://www.briskoda.net/forums/topic/291493-my-new-golf-gti/

sounds like I should test drive a 'normal' octavia 150 - but does seem that 17";s won't be an issue on the Vrs

 

Glad I'm not the only person who prefers more rubber!

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I've never understood this obsession with big diameter rims (the wheels of course are the same overall diameter).

They don't look any better at all. Neither (being the same diameter) do they "fill the wheel arches" - unless your eyesight is so poor that you cannot see the tyres.

I have lost count of the number of road tests I have read - of everything from Aston Martins to Fiat Pandas - where the writer says words to the effect of "Unfortunately our test car was supplied with the optional 20" Megabling wheels which made the ride harsh but which did nothing to improve the handling". Presumably these wheels were fitted for the benefit of the photgraper rather than the driver.

Disadvantage of big-diameter rims (not big diameter wheels - the wheels are always the same size):

- the rims cost more (a lot more, and if supplied on a new car, you don't even get the standard wheels back)

- the necessary low-profile tyres cost a lot more, and keep on costing a lot more every time they need replacing

- the low-profile tyres are more uncomfortable

- the handling is no better

- bigger diameter rims are usually uglier, being more elaborate, with hard-to-clean crevices and spokes either so close that you cannot clean between them or so sparse that the wheels look like bicycle wheels

- you can't see them from inside the car

- you can't see them from outside the car unless it is parked

Advntages of big-diameter rims:

- er ... um ... well, er ... ah ... um ... they make a fat profit for the dealer (and/or for Halfords).

The engineers who designed the car know what wheels it needs and that is what they specify. The marketing men may insist on bigger rims on the more expensive fancier variants to go with the increased decorative trim, but unless these varants have bigger brake disks they would run just as well on standard rims.

The standard rims are usually cheaper, simpler, stronger, easier-to-clean, more plain and therefore better looking than most alternative big-dimameter bling wheels. Leave those for Barry and his rusty old customised 1.2 litre Corsa, where they will go with his 12" diameter exhaust tailpipe.

(Not, of course, that I am biased in any way all ...)

It's bull**** posts like this that make me question why I even come on this forum.....

I am very very confused; has this got anything at all to do with whether or not VRS callipers now too big for 17" rims or was it just posted in the wrong place?

it was in response to post number 9 by the OP asking if TP was trolling with a comment re the differences. Don't be confused.

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I am intrigued by this.

I presume when you say "smaller wheels" you mean wheels of the same overall diamter but with smaller diameter rims, which do not require such low-profile tyres?

This would certainly increase ride comfort and reduce cost.

But if the overall wheel diameter were the same, I presume the only reason for the difference in fuel consumption etc. would be possibly lower rolling resistance with a tyre which did not have such a low profile?  If so, another very good reason for not wasting money on large-diameter rims and low-profile tyres.

 

 

Smaller rims, "taller" tyres to give the same rolling radius which usually (normally) weigh less than the equivalent big wheel/skinny tyre combination.  The added complication is that the mass on a larger wheel/tyre combination is also predominantly further out from the centre of the wheel so you have a higher moment of inertia - a flywheel effect, if you will.  The closer to the centre the mass is centred (excuse the wording), the easier to get it moving and likewise stop it, and change direction of travel.  Skinnier tyres do normally come with a wider tyre as well, so the increase in rolling resistance also has a negative effect on rolling resistance.  Increased rubber doesn't always mean better grip, despite what your gut instinct might say as when the pressure is spread over a larger area, the friction per unit area is lower.

 

It used to be a school experiment - holding the spinning bicycle wheel and standing on a turntable, turn the spinning wheel (a gyroscope in effect) and see how it turns you round.  Probably not allowed due to H&S now!

 

EDIT:  Yep - going slightly OT...

Edited 28 October, 201312 yr by philhoward

It's bull**** posts like this that make me question why I even come on this forum.....

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No BS - just fact.  There is no benefit whatever in big diameter rims and low-profile tyres, and many disadvantages.

However some people think that they look better.  That - and only that - is a matter of opinion.

Where is the BS in that?

 

 

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No BS - just fact.  There is no benefit whatever in big diameter rims and low-profile tyres, and many disadvantages.

 

 

So there's no benefit to handling from the less flexable side walls of low profile tyres which are also usually wider which improves grip and also no benefit from being able to fit larger brakes and also the improved cooling of the brakes?

 

Whatever.

My 2 pence on the exaggerated low profile tyres is that they would only benefit an exceptionally well setup car* running on an exceptionally well maintained surface.

 

*Tyre pressures are a lot more critical on low profiles than standard, for example and when driven at any decent pace you need very good and well maintained suspension.

 

I would prefer to have progressive breakaway, more damage resilience, more overall and guaranteed grip and an all round nicer ride.

 

 

 

A quick search found this thread, which sums up my thoughts succinctly. http://www.pistonheads.com/gassing/topic.asp?t=1084401 

 

"

Touring cars on the other hand use big rims purely for marketing purposes. I was involved in BTCC for many years as a chief race engineer and chassis designer. In the early 90s they ran 18" rims, but the manufacturers really wanted to promote 19" rims and eventually they insisted on switching to 19". We carried out a very comprehensive tyre test involving Dunlop, Michelin and Yokohama when the 19" tyres were under development. In all cases the 18" tyres were significantly quicker. The bigger rims allowed a bit more freedom in the suspension geometry and obviously more clearance for brake calipers, but 18" was a much better compromise overall.

 

As for road use, ultra-low profile tyres are entirely for show. They certainly compromise the ride and don't give the best grip levels. I'd say 17" is probably the best compromise between handling, ride and weight. 

"

 

So there's no benefit to handling from the less flexable side walls of low profile tyres which are also usually wider which improves grip and also no benefit from being able to fit larger brakes and also the improved cooling of the brakes?

 

Whatever.

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Correct.  I have never read any impartial report showing that the handling is improved by any of the normal larger rim and lower profile tyres size options offered by the vehicle manufacturer.  The tyre width is rarely much wider with the big-rim options, and even if it were it would be unlikley to offer more grip.  Less so, in fact, in adverse weather condiitons.

Even the most boy-racer, Jeremy Clarkson types of journalists never say "This car was OK but what it really needs is a set of phat wheels so that it would go round corners faster".  However what they regularly do say (read them) is "The ride was harsh, and the car would have bene much better on standard wheels". 

Note that we are not talking about modified cars here, or cars intended for track or competition use.

The design engineering team will have decided what size wheels are necessary, and that.is what they will specify.  They are well aware of the disadvanges (not just cost) of fitting larger diameter rims and lower profile tyres than a car needs, which is why they don't fit them as standard. 

If the performance of a particular version of that model requires larger brakes, then they will specify larger brakes and the wheels to suit.  They don't specify larger wheels and then say "Ooh, look, we could fit bigger brakes in there!"

 

 

Edited 28 October, 201312 yr by Stuarted

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Even the most boy-racer, Jeremy Clarkson types of journalists never say "This car was OK but what it really needs is a set of phat wheels so that it would go round corners faster". However what they regularly do say (read them) is "The ride was harsh, and the car would have bene much better on standard wheels".

Note that we are not talking about modified cars here, or cars intended for track or competition use.

So larger wheels with low profile tyres are ok as long as they're the standard fit ones but if they're optional they're no good??

More for vanity/appearance than performance IMHO.

 

A less compliant tyre (stiffer) won't "mould" itself to the road as well as a higher profile tyre - up until the point where sidewall flex becomes an issue (which is very much tyre dependant).

 

Jeremy Clarkson has also said that for photoshoots and TV footage, its best to have an oversteering car as it looks good - but in the real world one with slight understeer is safer by a long shot.

So larger wheels with low profile tyres are ok as long as they're the standard fit ones but if they're optional they're no good??

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"Larger wheels"?  Larger than what, if they are the standard fit?

Larger than the smallest ones needed to clear the brakes I assume, or the standard OEM size?  

 

The Yeti scenario being a case in point - the model came with 17" as standard (for the UK - which is a different discussion altogether), yet some owners managed to get the manufacturers to fit 16" wheels.

It's bull**** posts like this that make me question why I even come on this forum.....

Do you mean that there are parts of the post with which you disagree?

 

If so, how about a considered correction of the mistaken assertions?

Do you mean that there are parts of the post with which you disagree?

 

If so, how about a considered correction of the mistaken assertions?

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Well said.  I learn from this forum.

_ _ _

I happen to dislike darkly tinted windows, and couldn't think of any practical reason why anyone would want them.  I regarded them as sheer posing, and said so.

There were several replies, giving a number of very sensible, practical reasons why some owners liked the dark tint and I learned from this.

I still don't personally like them, but t least I now understand why many people do - it is clearly is not a choice always based just on vanity or posing.

There has been a similar useful discussion regarding the merits of built-in v. removable sat-nav devices.

I find it good that the people on this forum are mainly a sensible, down-to-Earth bunch whose prefences are usually rational and based practical considerations rather than fashion, posing or trying to be trendy.  And many correspondents are honest and realistic enough, when they prefer something just because they like the way it looks, simply and honestly to admit it and say so, rather than fooling themselves or trying to justify their choice on some spurious "technical" grounds.

An example might be my preference for wood trim, rather than brushed aluminium or (even worse in my opinion) carbon fibre.  I freely admit that this is a matter of personal preference, and my preference arises in part because I am a boring old-fashioned git  who loves traditional-looking things like wood trim and who regards carbon fibre trim as the stuff for trendy poseurs and boy-racers.  But as I said, this is purely based on my personal prejudice and a preference for the way it looks, There is no practical disadvantge to this choice and at least I can enjoy seeing it all the time while I am in the car, moving or stationary.  However I do not try to fool myself or insult other people's intelligence by pretending that it has any technical, practical or functional benefit.

Same with larger-diameter rims with low-profile tyres.  If that's what you prefer the look of and you are willing to put up with the many disadvantages that go with this choice, fine - that is your free choice.  But please don't try to pretend (or allow your self to be misled into thinking) that there is a practical benefit to such wheels.

 

 

Edited 28 October, 201312 yr by Stuarted

I've modded so many cars in my time and after having multiple sets of springs, springs and dampers from other models, Koni, bilstein, eibach etc as well as uprated anti roll bars, poly bushes and multiple sizes of wheel and tyre combinations... I'm convinced big alloys and low profile tyres are there for style and marketing purposes. I've not exactly restricted my modding budget on many of my cars but as I've learnt with experience, less can usually equal more in terms of wheel and tyre mods. There's a reason why my current two cars have less done to them than previous cars in the handling department. Even the Yeti on its relatively small 17" alloys and high sided 50 profile tyres can out perform 'sportier' cars down my favourite B roads simply due to the fact it has more give in the sidewalls and allows more natural compression without leaving it to the springs, dampers and bushes. Friends in their 18"/19" alloyed and elastic banded tyred cars can't carry the speeds through the roundabouts that I can, simply because the tarmac joins, drain covers and uneven surfaces throw them off line where as I can keep it planted and commit to the line. It's a simple fact and they have been the first to admit it!

I opted for the 18" wheel upgrade on my Octy III Elegance for two reasons, 1. As in my opinion the Golus 5 spoke wheel looked better than the standard wheel, and 2. As I have fat hands and hence need bigger gaps between the spokes so that I can clean the inner face of the rim without removing the wheel from the car, I like clean wheels!

I do however, accept that there is an effect on ride quality. I knew from experience comparing my Superb II Eleg which came with 18" wheels as standard, that it rode harsher than SWMBOs Octy II Eleg which sits on 16" wheels. When you measure the overall wheel/tyre diameter, SWMBOs are exactly +/- a few mm the same as on my Octy so obviously less rubber = harsher ride over the bumps, but it's a price I am prepared to pay for clean wheels!