Jump to content
SAU Community

Recommended Posts

im trying to work out what wheels to get for my stag.....does anyone know how much tollerence the attesa system has for rolling diameters? the rolling diameter of a 205/55r16 (the stock 16" wheel) is 632mm and the standard RS4s mags are 215/50r17 with rolling diameter of 648mm... how much either way can we go without upsetting the attesa?

D.

Link to comment
https://www.sau.com.au/forums/topic/219178-attesa-question/
Share on other sites

ahhh... the question that has been sked and answered a thousand times....

heres my answer from last time someone asked -

For long term issues tho, i nutted this out - this is my reasoning as to why something that seems so inconsequential can cause dramas -

A difference of 10mm in rolling diameter (Say 660mm front and a 650mm) rolling diameter rear tyre is a different of 31.42mm difference in distance travelled per rotation. Given that each rotation of a 650mm diameter tyre is about 2050mm, your larger tyre would rotate about 65 times every time your smaller one does 66times. So your larger tyre will have rotated one less time than your smaller one every 133 metres. If you do 1000 km a month, so 12,000km a year, then its a matter of your clutch packs coping with a difference of 90225 rotation difference every year. Thats a lot of wear and tear on your clutch packs, from a difference of 10mm.

if you have 225 tyres with 40 section, and 225s with 45 section, your difference in diameter will be 22.5mm (45% of 225 - 40% of 225, then multipliy it by two as we're dealing with diameter, not radius), so double the above figure. A differene of rotation of more than 180,000 times is what ur gonna get. How long do you think your clutch packs will last.....?

Hope that A) that makes sense and that B) my maths is correct!!

Bobbeh

Link to comment
https://www.sau.com.au/forums/topic/219178-attesa-question/#findComment-3865911
Share on other sites

so you're saying that even 10mm can be fatal over time?

the RS4s wheels are already 16mm larger rolling diameter than the standard 16" wheels... would the manuals have been adjusted at factory to suit this or are all manuals running their standard 17" wheels going to burn through clutch packs quicker than autos?

and, should i be trying to match rolling diameter of the standard 16" with the factory 205/55r16 or the 17s that came on my manual?

D.

Link to comment
https://www.sau.com.au/forums/topic/219178-attesa-question/#findComment-3865946
Share on other sites

it doesnt matter what the rolling diameter is - what matters is that is it the same rolling diameter front and back.

and yes, im saying it will be damaging over time. It is not the issue of changing the diameters, that doesnt hurt. Just make sure there is no difference between front and back.

Link to comment
https://www.sau.com.au/forums/topic/219178-attesa-question/#findComment-3865995
Share on other sites

so you can garruntee that changing the diameter wont effect the system, as long as they're all the same? coz i've been told that it will cause problems

D.

As long as the front left, front right, rear left and rear right wheels (wheels = rim and tyre) equal the same diamater/circumference, then you're safe.

For example, I'm running 235/40 tyres on 18" rims all round = no problems.

Apparently the ATTESA system can't handle even the slightest differences in circumference ... something I'm reading about at the moment for myself.

:O

Edited by RubyRS4
Link to comment
https://www.sau.com.au/forums/topic/219178-attesa-question/#findComment-3866133
Share on other sites

What happens when your 8mm deep tread wears down to the 1.5mm wear bars...? thats a 15mm change in rolling diameter. Doesnt matter. As long as front and rear is the same. The atessa system wont even know that the diameters have changed, as long as they are changed equally. only issue is that your speedo will be out. Bigger diameter means that your car will travel further with every rotation.

so you can garruntee that changing the diameter wont effect the system, as long as they're all the same? coz i've been told that it will cause problems

D.

Link to comment
https://www.sau.com.au/forums/topic/219178-attesa-question/#findComment-3866565
Share on other sites

yes that is very likely the reason. new rear tyres or just swap front to rear.

BTW it is difference front to rear that matters not the difference to stock wheels. I run 245/45/17 on mine which is pretty big - but no problems with attessa

Link to comment
https://www.sau.com.au/forums/topic/219178-attesa-question/#findComment-3866704
Share on other sites

What happens when your 8mm deep tread wears down to the 1.5mm wear bars...? thats a 15mm change in rolling diameter.

If you're talking new tyres (8mm deep tread) front and worn tyres (1.5mm wear bar) rears then its:

8mm - 1.5mm = 6.5mm

6.5mm x 2 = 13mm

Thats a 13mm change (not 15mm) in diameter :D

Sorry couldn't help myself :P

Link to comment
https://www.sau.com.au/forums/topic/219178-attesa-question/#findComment-3867394
Share on other sites

So if I do a hard left the inside tires will do less distance than the outside tires then a km down the road I do a hard right everything will right itself (just kidding) I plan to get new tires for the rear very soon. LOL

I am going on a trip this weekend so I will swap front to rear and see how it goes.

Thanks for your help.

Link to comment
https://www.sau.com.au/forums/topic/219178-attesa-question/#findComment-3869927
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Ok i will get those 310mm. I found one but on a different site. This is the description on those...is it ok? Technical parameters: - Axle: front. - Disc type: ventilated. - Number of holes: 5. - Disc diameter: 310mm. - Total height with center: 54mm. - Thickness (new/min.): 30/28mm. - Designed for brake calipers manufacturer: Sumitomo.
    • You Gregged a whole racetrack!?
    • Look for broken wire or bad connector at the motor. Might not be it, but is worth starting there, as it is easy.
    • Hi everyone, I’m having an issue with my R32 GT-R. Sometimes, when the car goes over a bump or experiences some vibration, the 4WD warning light comes on the dashboard. When I check the code from the control unit in the trunk, it shows Code 19 – ETS Motor. However, everything seems to be working fine — if I turn off the engine and restart the car, the light goes away and everything functions normally. Has anyone experienced this before? Where should I start troubleshooting this issue? Thanks in advance!
    • I'm back from the dyno - again! I went looking for someone who knew LS's and had a roller dyno, to see how it shaped up compared to everything else and confirm the powerband really is peaking where Mr Mamo says it should. TLDR: The dyno result I got this time definitely had the shape of how it feels on the road and finally 'makes sense'. Also we had a bit more time to play with timing on the dyno, it turns out the common practice in LS is to lower the timing around peak torque and restore it to max after. So given a car was on the dyno and mostly dialled in already, it was time for tweaking. Luis at APS is definitely knowledgable when it came to this and had overlays ready to go and was happy to share. If you map out your cylinder airmass you start seeing graphs that look a LOT like the engine's torque curve. The good thing also is if you map out your timing curve when you're avoiding knock... this curve very much looks like the inverse of the airmass curve. The result? Well it's another 10.7kw/14hp kw from where I drove it in at. Pretty much everywhere, too. As to how much this car actually makes in Hub Dyno numbers, American Dyno numbers, or Mainline dyno numbers, I say I don't know and it's gone up ~25kw since I started tinkering lol. It IS interesting how the shorter ratio gears I have aren't scaled right on this dyno - 6840RPM is 199KMH, not 175KMH. I have also seen other printouts here with cars with less mods at much higher "kmh" for their RPM due Commodores having 3.45's or longer (!) rear diff ratios maxing out 4th gear which is the 1:1 gear on the T56. Does this matter? No, not really. The real answer is go to the strip and see what it traps, but: I guess I should have gone last Sunday...
×
×
  • Create New...