Reducing rim size on vRS

[applesee]

Thanks DunlopRS... it looks, ummm, stock...
Reading the success you had has re-enforced that the standard Skoda 16" alloy is the right path to go...

[DunlopRS]

Thanks DunlopRS... it looks, ummm, stock...
Reading the success you had has re-enforced that the standard Skoda 16" alloy is the right path to go...

..... Yes. They are growing on me. Perhaps the memory of how good the neptunes look is fading.
However, the neptunes will not be going back on until its sale time (perhaps quite a few years - I love the car).

Let us know how you go sourcing some rims goes - is yours an RS? - if so I would be very interested in experience with 3rd party / non-VAG fitments.

[Diesel_vert]

For my driving I am VERY happy with the change to 16” rims. I went with 205 55 continental conticomfort 5s. I no longer feel every join in the concrete on the hume in spine and there is no reason at all to slow down at places on the Hay plain for fear of breaking the car (or the significantly worse council maintained roads off the major tracks). They are much quieter and get the power onto the road better (much, much harder to make the wheels spin).

Another side effect of going higher in profile is the larger range of less "sporty" tyres. Trying to find a touring tyre in 225/40 R18 is not easy.

Not sure (have no idea) if any VW group 16 would fit over a RS disk/caliper (there is enough but no excess in clearance with mine) – but it seems that you may be able to find 3rd party alloys that fit if you can find a salesman that is interested in spending the time……
Good luck (will be taking my wife’s focus to the snow…).

They'd certainly have a very high chance of fitting without issue.

the reason for going 205/55 R16...
thinking that I might be able to get away with 6.5J instead of 6.0J

You might get away with it if you fit really small chains, like no larger than 5~6 mm or something, but I'm afraid I don't have any experience with snow chains.

I cant quite see how a 205/55x16 would have more resistance to wheelspin than a 225/40x18 unless the 18s were crappy tyres.

A tyre with a higher profile with a taller footprint, which doesn't lose contact with the road as much compared to less compliant low-profile tyres and newer or fresher rubber may explain his observations.

[Mysticality]

A tyre with a higher profile with a taller footprint, which doesn't lose contact with the road as much compared to less compliant low-profile tyres and newer or fresher rubber may explain his observations.

Taller profile on the tyre (more rubber on the side) = larger flat spot on the ground.
Go check out how 4WD tyres work offroad, for an exaggerated example.

[Diesel_vert]

Taller profile on the tyre (more rubber on the side) = larger flat spot on the ground.
Go check out how 4WD tyres work offroad, for an exaggerated example.

On the same vehicle, the surface area doesn't change much - mainly just the shape.

[DunlopRS]

If you're talking about the letter "V" on the tyre's sidewall, it's the speed index which represents a max. speed of 240 km/h.

Sorry – should be less verbose / less cryptic or even reduce the off topic commentary…..
Was meaning the “v” in the vRS……..

[Diesel_vert]

Sorry – should be less verbose / less cryptic or even reduce the off topic commentary…..
Was meaning the “v” in the vRS……..

Ah, I see.
No worries then, haha.

[applesee]

Let us know how you go sourcing some rims goes - is yours an RS? - if so I would be very interested in experience with 3rd party / non-VAG fitments.

Yup, it is a RS. Will see how I go...

You might get away with it if you fit really small chains, like no larger than 5~6 mm or something, but I'm afraid I don't have any experience with snow chains.

Yes, hoping that I'll be able to get away with 9mm chains on the 16x6.5J ET50 rim. If max chain size for 16x6J rim is 15mm and 6.5J rim is about 12.7mm wider than 6J rim (i.e. ~6mm more on either side), then 9mm chain should be ok?!

I wonder if there's a tyre+wheel calculator that compares the width profile of 205/55R16 tyre on a 6J rim versus 6.5J rim...

[gldgti]

Wow mate - they look HEAPS better on a white wagon than they did on my black one.

I reckon it looks tough

[gldgti]

I cant quite see how a 205/55x16 would have more resistance to wheelspin than a 235/40x18 unless the 18s were crappy tyres.
.

Basically, because the 16" tyres are more flexible radially and tortionally, they will conform much better to the surface they are resting on and employ the tread much better. Very low profile tyres are very stiff torsionally, and under all but ideal circumstances will have much less success gripping the road surface.

Extreme examples being drag racing tyres.

Also, there's every chance that even though the 16's may have a slightly smaller over all diameter, the reduction in width and energy transmitted through to the body because of vibration on rough roads, and j (moment of inertia) of the wheel, all aid fuel economy.

[DunlopRS]

Wow mate - they look HEAPS better on a white wagon than they did on my black one.

I reckon it looks tough

Thanks gldgti – yes, the looks are growing on me – the red calipers still are reasonably visible thru the wheel too. Especially now its covered in (almost) mud from road works in the rain it looks very “purposeful” rather than a “show pony” (please don’t anyone take offence at that remark – I really love the look of a nicely set up car such as the “dark arrow” – superb! - but operationally they do not work for me… - each to his/her own needs) - all mine needs now is the spotlights…….

Basically, because the 16" tyres are more flexible radially and tortionally, they will conform much better to the surface they are resting on and employ the tread much better. Very low profile tyres are very stiff torsionally, and under all but ideal circumstances will have much less success gripping the road surface.

Extreme examples being drag racing tyres.

Also thanks to gldgti for the physics/engineering lesson – could visualise this but not ‘verbalise’ it. FWIW one of the few Top Gear episodes I saw demonstrated this with I think a HSV Commodore on a track. They went up a rim size by I think 1” and over repeated runs the taller rims were seconds slower than the smaller ones. On the 18” I had learnt to come off the throttle significantly as the turbo lag dissipated to try & reduce the incidence of spin (my first turbocharged car - do not need to now with the 16"s) – it was always interesting watching the other half who does not drive the RS often having the wheels spinning at almost every significant acceleration around town. I would not have got 25k km out of those (expensive) tyres.

Covered 475 km this afternoon with an indicated fuel consumption of 5.2 L/100 km at the speed limit (gen 110 – normally notice a significant increase in consumption from 100 to 110) with the kids and luggage. Have the kids working on some note taking comparing mileage markers with the odometer and satnav – the odo seems much closer to the ‘actual’ with my setup than I expected – will report when I have covered about another 800 km tomorrow. With this setup the vRS really eats the miles on any sealed / semi sealed surface.

[gldgti]

Great result mate. Sounds like perhaps you really have jumped into a subvariant "GT" class, reminicent of the 90's european sold VW's of the same badging - Golf Mk2, 3, and 4 all came out in diesel GT variants - diesel economy and torque mixed with GTI-esque suspension but they usually had more "normal" sized wheels and they were a lot harder to pick out on looks than a GTI. You could even get syncro and later 4motion ones.... wish they came here

[kaanage]

Tyre (and indeed suspension) compliance are highly underrated by many on this forum. Really glad to hear the outcome has been so good.

[DunlopRS]

Tyre (and indeed suspension) compliance are highly underrated by many on this forum. Really glad to hear the outcome has been so good.

Thanks – my main reasons for going with 205/55-16 on the 6.5” rims were
1. Skoda plated/recommendation for the rim size.
2. Should be no problems putting snow chains on.
3. Common fitment – have not that long ago spent most of Sat on a 2 day weekend away scouring used tyre heaps in a major regional centre to get a suitable tyre to get me home following staking a sidewall on an Aus built car – no new ones the right size in town (population 20000+…..).
4. Was most likely to get the result that I was after – and it has.

You realise that the smaller diameter of the 205/55x16 will make your fuel economy look better even though it's not? Also, 15,000km on the odo will now be more like an actual 13,500km (I think that's what I worked out mine was).

Have had a go at determining odo accuracy with this set up (new rubber - could not say that for the 18s I had as the 2900km trip would have been more than 10% of the tyres life…).

Firstly, comparing distance travelled by satnav to odo (trip meter) distance. Criteria of >40 km but <99 (to get reasonable distance but keep satnav to 0.1 km intervals). Ten observations, odo 0.3% less than satnav (range 0 to 0.6% less).

Secondly, comparing distance travelled by roadside marker to trip meter. Criteria > 40km. 14 observations, over distances of 40-130 kms. Odo 0.4% less than mileage markers (range 0.3 to 0.7% less).

0.4% or 400m in 100 km is likely close to the errors associated with the measurements – I am happy to say the odo on these tyres represents reality (and the odo seems to be showing slightly less (if anything) that the actual distance travelled).

As for the speedo – didn’t think to get the kids going with a stopwatch over some long stretches – will leave that lesson in 2D motion for the kids to the next trip out west. A number of cameras did this for me – I hope I will not get any surprises in the mail in the next couple of weeks……..

So, over 2900 km in the week the indicated fuel consumption was 5.5 L/100 km or 51.4 mpg in the old language. Happy to call that it – not sure how accurate the fuel metering is but it’s likely as good or better than estimating based on fuel bowser measurements and degree of tank fill.

Moving away from any OCD tendency (or is it just my Germanic heritage…. ) to real life & work now…….

[brad]

As for the speedo – didn’t think to get the kids going with a stopwatch over some long stretches – will leave that lesson in 2D motion for the kids to the next trip out west. A number of cameras did this for me – I hope I will not get any surprises in the mail in the next couple of weeks……..

You shouldn't unless you were deliberately speeding. 100km on the speedo should be around 93kmh actual with those tyres.