Reducing rim size on vRS

[DunlopRS]

Hi All,
Always one to be a bit different (why I have a skoda??), I am considering changing my 18" rims to 17" or less on my MY2011 vRS. I do a lot of driving on country roads and as much as I like the look of the 18s the ride on the broken bitumen (or bitumen lined holes) is very harsh and I feel I am at risk of breaking something……
Tyre placard has the following options:
7.5j18 with 225/40 r18 (92V) - as standard
7j17 with 225/45 r17
6.5j16 with 205/55 r16 – as is the spare on a steel rim
My local tyre man says I am unlikely to get a 16” alloy on – there is not much room around the spare rim (steel) which is on at the moment.
Has anyone any experience in going this way (instead of putting 19s on)? Does going to a 45 series tyre from a 40 make much difference (noting for the same money I could get a much better 17” tyre than an 18…)
Thanks

[kaanage]

My experience with is with my Polo but it should be relevant.

After installing a suspension kit, I found the ride too firm for daily use so I went from 195/55R15 down to 175/65R14 with a huge improvement. Going from a 40 series to 45 won't have as much effect but it should still take the edge off sharp bumps and holes.

I'd still check if you can find a 16" rim that you like which will fit over the brakes. That certainly would noticable.

Fully agree about the tyre cost effect too (yet another reason not to go for big wheels...)

[zei20t]

Here you go:

http://www.vwwatercooled.org.au/forums/f24/oem-octavia-16-alloys-72911.html

Make sure:

Offset is ok
Wheels clear brakes
Rolling diameter is the same (or pretty close) to the factory 18s

[kaanage]

yeah, that was my immediate thought but those are off a 1.9TDi which would have smaller brakes than a vRS.
They may not clear the brakes - the OP needs to find a Golf/Octavia with 16" 5/112 wheels to test (actually, just sitting the wheel from an older Golf on to the hub and seeing if it all clears would do)

[team_v]

16" wheels off the Tiguan might be an option as well as they run large brakes.
Offset might be a killer though.

[BluChris]

Actually the 1.9 TDI came with 15s, just like the dinky little things sitting on my car (and the current 90 TSI). 16s were standard on the Elegance petrol and probably 2.0 Elegance diesel. Not sure it makes much difference to whether they will fit. On my car, I can just get fingers and shallow sponge between the disk and rims for cleaning

[K1W1]

6.5j16 with 205/55 r16 – as is the spare on a steel rim
My local tyre man says I am unlikely to get a 16” alloy on – there is not much room around the spare rim (steel) which is on at the moment.

16" steel rims and some fake plastic caps would be a really cheap and practical solution if that was the aim.

[kaanage]

Actually the 1.9 TDI came with 15s,

That may well be but the ones that were linked are off a 1.9TDi (maybe optioned up at purchase time).

The point was that they may not fit the OP's vRS since it is guaranteed to have larger brakes than the 1.9 TDi.

[noone]

Tyre choice and tyre pressure can make a big difference. I recently had 24 PSI in the rear of my car on bad roads, handling was fine although I'd recommend staying in VW and manufacturer recommendations.
Wheel offset and width also will have some impact, Kaanage should be able to provide more detail on this, his understanding of the geometry and physics is much greater than mine

[gldgti]

**EDIT** I think the calipers for all are the same, but the VRS has 312mm disks where the other models have 288mm. As to whether they will fit under 16" alloys, well I'm not entirely sure but its not hard for me to give you an inside diameter measurement (when I get home)

As to offset, they will fit perfectly.

noone - I agree that the tyres and pressures are important, but I have done lots of driving on terrible (almost criminally bad) roads on the mid north coast and you need to run really high pressures with low profile tyres just to make sure you dont end up with dented rims all the time... it sucks, and is inevitably jarring and uncomfortable. on the other hand, >50 profile tyres just make it that much easier.

[DunlopRS]

Thanks guys,
Yes min ID will help see if they are a goer. Not quite the look I'm after but it may be a good start.

As for pressure, I am having to keep 45psi in the 18s to stop interesting looking wear marks on the sidewalls (wear across the surface looks perfect at about 20% tread - after only 22k km - can't stop the front spinning and higher profiles might also help that..). Makes for an interesting ride on unsealed roads (almost bought the scout but being an ex motorcyclist the extra power/torque of the vRS got me ....... perhaps I cannot decide which side of 40 I am on.....).

[gldgti]

Thanks guys,
Yes min ID will help see if they are a goer. Not quite the look I'm after but it may be a good start.

As for pressure, I am having to keep 45psi in the 18s to stop interesting looking wear marks on the sidewalls (wear across the surface looks perfect at about 20% tread - after only 22k km - can't stop the front spinning and higher profiles might also help that..). Makes for an interesting ride on unsealed roads (almost bought the scout but being an ex motorcyclist the extra power/torque of the vRS got me ....... perhaps I cannot decide which side of 40 I am on.....).

Yeah I hear you. When I got my octavia the 16's were so comfy but I bought the 17's because I do most of my driving now on the freeway, which is fine. But, every time I visit my folks up the coast I have to be soo careful, and I've only got the 17's on there. I can only imagine how difficult it must be on 18's.

[gldgti]

OK, the ID of the wheel measured in line with the hub face is 360mm (that is the smallest it gets to). That does not include the thickness of the stick on balancing weights.

I had a looky at my octavia front brakes, and looks like the caliper needs another 18-20mm outside the OD of the disk.

If your disks are 312mm, then that means you need about 356mm inside the wheel to clear (with some margin in there)... I'd say it will fit with a bit to spare but its not really a guarantee

[DunlopRS]

Thanks,
From my very rough measure through the wheel in the dark I need ~340-350 to clear the caliper - in line with your estimates. I will have one of the front wheels off tomorrow night to replace the puncture repair - OK if we talk after that?

[kaanage]

Tyre choice and tyre pressure can make a big difference. I recently had 24 PSI in the rear of my car on bad roads, handling was fine although I'd recommend staying in VW and manufacturer recommendations.
Wheel offset and width also will have some impact,

Funny how no one even thought to mention the tyre type and pressure and they will indeed have a big effect on ride but gldgti has basically said it - with low profile tyres, you can't drop the pressure too far else you risk denting/cracking rims on poor surfaces. Since DunlopRS is forced to run 45psi to prevent wheel and tyre damage, it's no wonder that he dislikes the rideof his car.

The width works inversely with the profile (wider tyre => lower profile for the same rim size) and one of the unfortunate facts of the universe is that it is the air volume held by the tyre that supports the car, not the tyre itself, so to maintain the volume when going to a larger rim diameter, you are forced to go to a wider tyre which in turn lowers the profile etc, etc...

Reducing offset will soften the ride slightly as the leverage of the tyre on the springs is increased. The effect is fairly small though, and you wouldn't be likely to fell much effect without going to the point where the tyre starts protruding from the guards. Of course, reduced offset also increases grips slightly due to the track increase but I don't like the associated increase in scrub radius on the front as I find the effect on steering response unpleasant (others may not mind it).