Reducing rim size on vRS

[kaanage]

Personally, i think you'll be pretty disapointed in the result though.

Because of the taller tyre profile (since the vRS is the equivalent of a GTi)?

225/55R16 is almost spot on for rolling diameter, has the same contact patch and would be only marginally less responsive.

If the improved ride means DunlopRS doesn't have to slow down for rough patches or run really high tyre pressures and have the car crashing about, then that's a real world performance gain.

Running 45 psi is a recipe for disaster. ..... That sort of pressure on any road surface with irregularities is simply asking for a monumentally large blow out and instant tyre deflation to occur when you roll over something that is sharp and pointing at the tyre.

Tyres are far tougher than that - damage from sidewall pinching over sharp edges is far more likely than any possibility of puncturing due to lack of pliability

[Diesel_vert]

A few folk on briskoda have fitted RS 312mm discs & carriers (the std calipers will fit) to their 288mm/16" cars & it works as long as the wheel weights don't get in the way. You have to test fit your wheel of choice though as profiles vary.

I had a strong suspicion they'd fit.

My sweet spot would be 17x7.5 ET50 with a 235/40x17 if it doesn't throw the speedo into over-reading.

I think 235/40 R17 (1891 mm) is too small. It'd be like fitting the equivalent of a 205/40 R18 (1895 mm) tyre.

And although it's more compliant than 225/40 R18 (1943 mm), it's actually less compliant than 225/45 R17 (1934 mm).

225/55R16 is almost spot on for rolling diameter, has the same contact patch and would be only marginally less responsive.

I think 225/55 R16 (1995 mm) is too big. It'd be like fitting the equivalent of a 245/40 R18 (1992 mm) tyre.

In terms of response, it's only better than 195/65 R15 (1937 mm), which results in an overly comfort biased setup IMO.


My 2 cents:
I think sticking with the OEM 16" wheel dimensions with the OEM tyre size of 205/55 R16 (1928 mm) is the best way to go.

If the improved ride means DunlopRS doesn't have to slow down for rough patches or run really high tyre pressures and have the car crashing about, then that's a real world performance gain.

+1111111

Probably the most underrated quality in any car - be it for racing or road use.

Tyres are far tougher than that - damage from sidewall pinching over sharp edges is far more likely than any possibility of puncturing due to lack of pliability

I tend to agree.
As long as the inflation pressure doesn't exceed whatever is on the tyre's sidewall (typically 350 kPA or 51 psi for high speed passenger tyres) it should be fine, if not ideal.

[kaanage]

I think 225/55 R16 (1995 mm) is too big. It'd be like fitting the equivalent of a 245/40 R18 (1992 mm) tyre.

In terms of response, it's only better than 195/65 R15 (1937 mm), which results in an overly comfort biased setup IMO.

Whoops!! Sorry for the typo - I should have typed 225/50R16

[Diesel_vert]

Whoops!! Sorry for the typo - I should have typed 225/50R16

Ah, I see. 225/50 R16 (1928 mm) does indeed have an identical rolling circumference to 205/55 R16 (1928 mm) and is as compliant. It's also actually a tiny bit wider than 225/40 R18.

In fact, a 225/50 R16 tyre on a 6.5 J x 16 wheel can potentially be slightly wider (by up to 3mm) than a 225/40 R18 tyre on a 7.5 J x 18 wheel. But this ultimately varies depending on the make and model of tyre due to tolerances.

[DunlopRS]

, then that's a real world performance gain.

Real world performance is what it is all about. This is the quickest car I have ever owned – and that includes a number of big sixes – its ability to get past road trains quickly with no fuss is phenomenal. However dropping off the bitumen half way past is something I do not enjoy on 40 series tyres……..

[gldgti]

To whom it may concern....

The wheels fitted nicey and DunlopRS is happily on way home -

Once fitted up, there was a good 6mm clearance between the balancing weights and caliper.

Win for all!

[kaanage]

Everybody wins

It'll be interesting to hear DunlopRS's long term verdict.

[gldgti]

My own take - on 16's -

When I first got the octy with the 16's, I felt that the steering response, handling and ride were all excellent. The only thing I didnt like was the looks.

I bought some badly gutter rashed audi ronals, 17x7.5 et50, bogged and resprayed them, got tyres and fitted them.

Handling over bumps with the 17's is notably worse (significant increase in sprung weight) but on a smooth road the drive is nicer. I dont think anyone would notice an ultimate performance difference in normal road driving.

I would say provided the quality of the rubber is good, and using the 55 series tyres, the real world performance could only benfit.

I would also disagree with K1W1 - 45 psi is not too high for just about any low profile tyre. Most 45 and lower profile tyres have printed a maximum inflation presure between 45-50psi. The last two sets of "extra load" tyres I have bought (due to the bad roads) have been 57psi max inflation pressure.

I think statistically I do enough km on bad roads ridden with corrugations and potholes to have had some kind of exploding tyre by now - but the only problem I've ever had is from running 45 series tyres at below 38psi - when the rim was damaged and the tyre deflated.

Still, death may come for me yet.

kaanage - thankyou, I had no idea there was also a dancing carrot, chillie and (i guess) cucumber. Awesome.

[DunlopRS]

Thanks to all for the comments.

The wheels fitted nicey and DunlopRS is happily on way home -
Once fitted up, there was a good 6mm clearance between the balancing weights and caliper.
Win for all!

Thanks to gldgti for indulging me in a try-before-you buy. As noted the fit is good.
Great trip today – 5.1 L/100 km from Canberra to the end of the M7 (downhill) and 5.5 L/100 km OA for the 731 km round trip……

Everybody wins

It'll be interesting to hear DunlopRS's long term verdict.

I will source some new tyres in the next couple of weeks and let you know of the results after my next sortie into the bush.

[brad]

I think 235/40 R17 (1891 mm) is too small. It'd be like fitting the equivalent of a 205/40 R18 (1895 mm) tyre.

And although it's more compliant than 225/40 R18 (1943 mm), it's actually less compliant than 225/45 R17 (1934 mm).

woops. I meant 235/45x17

I think 225/55 R16 (1995 mm) is too big. It'd be like fitting the equivalent of a 245/40 R18 (1992 mm) tyre.

In terms of response, it's only better than 195/65 R15 (1937 mm), which results in an overly comfort biased setup IMO.

I'm running 225/55x16 at the moment. I'd rather run them than 205/55x16 (which I have done). A bit more grip, you can run them at 36psi all the time, responsive & the sidewalls are so tall you don't have to worry about kerbing your rims. You can belt up driveways & through potholes without an issue. They make the speedo 100% accurate rather than the 10% under that the OEM 205/55x16 gives you.

I drive on some really lousy private roads at silly speeds & they work great.

The cons are that the tyres weigh 10kg & the Audi 16x7.5 rims I have weigh 10kg.

Before the Audi rims I had a set of 17x8 ET35 BBS with 225/45x17 which weighed 18kg. Got rid of them because they had too much poke & the previous owner had kerbed them too much.

And before that the 16x6.5 ET51 with 205/55x16 that weighed 17.2kg.

For my next set of wheels (I change wheels when the tyres wear out - it's like having a new car), I'd like 17x7.5 ET45-50 with 235/45x17 weighing around 17kg. I think that might be the sweet spot for me.

My 2 cents:
I think sticking with the OEM 16" wheel dimensions with the OEM tyre size of 205/55 R16 (1928 mm) is the best way to go.

See above re: innacurate speedo. Also the odometer is too far out. 15,000km on the odo is ~14,000km actual.

To the OP: I'd still only drop to 17". vRS come out stock in most parts of the world with 17". Easy to justify the change to your insurance company.