Wheel advice

[DUBGTI]

Hey guys I am looking to get some new wheels and tyres for the RS wagon, has anyone had experience with larger than OEM size of 225 40 R18 x 7.5 with 51ET I'm trying to figure out what is the fattest tyre I can fit under the guard, I plan to lower the car at least 25mm maybe double that if possible.

Is it possible to run a 19"x 8.5" with a 235 35 or 245 30? what fits best? It seems a 225 35 R19 is the closest to stock rolling diameter being -0.45% out and doing 59.73mph at a speedo reading of 60mph (tyre size calc worked in mph).

What are you guys running on ya Octy's? would love to see some pics of different wheel combos

cheers guys,

[zei20t]

I have 19x8.5" with a 235x40x19 tyre. I don't notice any rubbing except on hard turns on the outside wheel when the suspension compresses. harder spring/shock will help that.

[donweather]

Zei do you have stock or lowered suspension. And what ET are you running?

[DUBGTI]

Hey can I ask how accurate your speedo is? the tyre calculator shows your setup to be almost 5% larger than stock and would result in a roughly 5km/h difference from stock. At an indicated 100km/h on your speedo your actual speed would be roughly 95km/h, but how accurate are they at that speed to start with, most cars would read less than 100km/h at an indicated 100km/h to start with, is this increased with your size tyres?

I am trying to stay as close as possible to the stock rolling diameter to avoid and potential issues be it with the car or the law
I'm just cautious off speeding fines......haha, I'd be thinking I'm going at the speed indicated on the speedo, but actually doing another.

cheers

[donweather]

I literally ordered a new set of tyres 225/40/R18 today for my new set of rims 18*8 ET45 as I was super keen on the 235/35/R18 but mysticality talked me out of it after saying I'd have serious scrubbing issues (more so when towing my jetski). So I'm keen to hear what Zei has to say.

[Dutch77]

zei20t can confirm or correct me but IIRC he was looking at VMRs or similar once upon a time, so is probably ET45 as well.

[DUBGTI]

I have been toying around with tyre sizes and referring to tire rack for load and speed ratings in that size, I can't seem to find a 92Y in anything other than stock size, is it required by law? or by insurance in case of a void accident claim? an 88Y is the highest rating I can find atm.

It is a weight difference of 560kgs for the 88 to 630 for the 92, Y being 300km/h on both, I am pretty sure I reach that speed every day on the way to the shops..... seems rather high for a passenger vehicle in australia to need a 300km/h rating?

It might seem that it is more important to follow the weight/load rating than it is the speed ratings.

[tigger73]

I have been toying around with tyre sizes and referring to tire rack for load and speed ratings in that size, I can't seem to find a 92Y in anything other than stock size, is it required by law? or by insurance in case of a void accident claim? an 88Y is the highest rating I can find atm.

It is a weight difference of 560kgs for the 88 to 630 for the 92, Y being 300km/h on both, I am pretty sure I reach that speed every day on the way to the shops..... seems rather high for a passenger vehicle in australia to need a 300km/h rating?

It might seem that it is more important to follow the weight/load rating than it is the speed ratings.

What matters is what specs are on your vehicle wheel/tyre placard. You have to meet/exceed the minimum specified for the diameter rim you're running. And yes that's for both load and speed.

Sometimes there's a reason tyres are cheap on the online stores. It can be speed/load rating and also manufacture date. You needed to check all that out before buying as most often these can't be returned.

If you're looking for some decent tyres at a good price then give Goodyear Croydon (Vic) a call. They have a range of common VAG sizes in their F1A2 performance tyre at competitive prices to tyre rack. Plus your getting warranty and guaranteed fresh rubber. There's quite a few people that have bought tyres from here. Check the wheel/tyre forum for details.



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[brad]

Hey can I ask how accurate your speedo is? the tyre calculator shows your setup to be almost 5% larger than stock and would result in a roughly 5km/h difference from stock. At an indicated 100km/h on your speedo your actual speed would be roughly 95km/h, but how accurate are they at that speed to start with, most cars would read less than 100km/h at an indicated 100km/h to start with, is this increased with your size tyres?

I am trying to stay as close as possible to the stock rolling diameter to avoid and potential issues be it with the car or the law
I'm just cautious off speeding fines......haha, I'd be thinking I'm going at the speed indicated on the speedo, but actually doing another.

cheers

As all these vehicles seem to differ, best to check with reasonably modern GPS. As an indication, I've gone up 4% (+20mm diameter) and am still 2kmh under at 100kph. From the factory my speedo was 10kph out at 100kph

I get the feeling that zei20t has made a typo & has 235/40r18 but maybe I'm wrong.

Keep in mind that you also have to consider maintaining the correct load rating & this gets difficult when you get into 19"s.

[harlie]

Mine was in for an alignment to sort the rear geometry during the week. Local tyre shop recommended I go to 235/40R18 next time - cheaper tyres ect ect - they are 8mm larger in diameter. are they wrong?

Now I'm shopping for wheels - 18x8 et45. during balancing they noticed one of my badly scratched neptunes has what he calls a flat spot, (I call it buckled) on the inner rim - that will be the vibration at 100kmh.

[brad]

Harlie - you need to know how far wrong your speedo is at the moment before you make changes

[donweather]

If you're looking for some decent tyres at a good price then give Goodyear Croydon (Vic) a call. They have a range of common VAG sizes in their F1A2 performance tyre at competitive prices to tyre rack. Plus your getting warranty and guaranteed fresh rubber. There's quite a few people that have bought tyres from here.

That's exactly who I bought them from today. But I completely forgot to ask if they were 92Y. I hope they are!!!

Edit: just checked they're website. 92Y. Lucky!!

Tyre Search, Goodyear Autocare, Australia

[tigger73]

DUBGTI let me know if you want to test your speedo. I have a GPS speedo in my possession at the moment.

[Dutch77]

Mine was in for an alignment to sort the rear geometry during the week. Local tyre shop recommended I go to 235/40R18 next time - cheaper tyres ect ect - they are 8mm larger in diameter. are they wrong?

Now I'm shopping for wheels - 18x8 et45. during balancing they noticed one of my badly scratched neptunes has what he calls a flat spot, (I call it buckled) on the inner rim - that will be the vibration at 100kmh.

Tyre shop is correct on both counts (but I agree with Brad's advice, check it out before playing is preferable).

8mm larger diameter, which means you will be going a fraction slower than indicated. 235/40/18s are often cheaper than 225s as the 235s are a common Falcodore 18 inch fitment and thus bought in large quantities.

Loads of wheel options, check out the Mk7 thread if you like as plenty of 18x8 ET45 or similar wheels in there.

[harlie]

Harlie - you need to know how far wrong your speedo is at the moment before you make changes

Thanks, my Speedo reads 5% over what the GPS says. Speedo says 100, GPS 95. 60/57 ect ect. So the 1.2% circumference that 235 is over 225 is not an issue, will bring the numbers closer. I as more concerned with clearance.