tyre weight, tyre weight saving potential and 20" are lighter then 19" (surprise)


  1. Welcome to Audi R8 Forum : Audi R8 forums – General discussion forum for Audi R8

    Welcome to Audi R8 Forum : Audi R8 forums - a website dedicated to all things Audi R8.

    You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, Join Audi R8 Forum : Audi R8 forums today!
     
Page 1 of 2 12 LastLast
Results 1 to 10 of 15

Thread: tyre weight, tyre weight saving potential and 20" are lighter then 19" (surprise)

  1. #1
    Senior Member
    Join Date
    Oct 2016
    Location
    switzerland
    Posts
    769

    tyre weight, tyre weight saving potential and 20" are lighter then 19" (surprise)

    Some very interesting facts about how tyre weight differ per manufacturer and even manufacturer Spec in the same size and also the myth that 20" is far heavier then 19".
    If I didn't mention the manufacturer spec (eg RO1, N1, N2..) then it is the standard aftermarket tyre. All tyres here (except Hankook, their good test results are bought...) are on the same high quality level!
    Some weights:

    REAR:

    tyre size 305 30 20

    Conti 6 FR XL: 12,8 kg
    Michelin PS4S: 13,8 kg
    Pirelli Zero NO (strongly reinforced for Porsche 911! but more grip): 13.1kg
    Pirelli Zero RO1 (Audi R8 Gen2) : 12.1kg
    Hankook: 13,86kg (smallest width of all, in fact one size smaller wide then all others)

    => weight saving potential 1.76kg per tyre

    tyre size: 305 30 19
    Conti 6 FR XL: 10,99kg
    Pirelli P Zero N2 : 14,3kg
    Pirelli P Zero RO1: 13,21kg
    Michelin PS4S: 12,669kg
    Michelin PSS: 12,56kg
    Hankook Ventus S1: 13,262kg
    => weight saving potential 3,3kg per tyre!!!

    FRONT

    Tyre size: 235 35 19

    Pirelli P Zero: 10.2kg
    Pirelli P Zero RO1: 9,87kg
    Conti 6 FR XL: 13,427kg (no typo mistake!)
    Conti 5P FR AO: 9.8kg
    Hankook Ventus V12 evo 2: 10,022kg
    Hankook S1 Evo 2: 11kg
    Michelin PSS: 9,96kg
    Michelin PS4S: 10,22kg

    => weight Saving potential 3,67kg per tyre, but except Conti 6 they are pretty close around +/- 100g. Choice of exact tyre is by rear as much bigger differences

    Tyre size: 245 30 20

    Conti 6 FR XL: 9,96kg
    Michelin PS4S: 10,38kg
    Pirelli P Zero: 11,2kg
    Prielli P Zero RO1: 9,67kg
    Hankook S1 evo: 10,32kg
    => Weight saving potential 1.5kg per wheel

    Tyre Size: 255 30 20
    Pirelli P Zero RO1: 10.4kg (I am currently running this)
    Conti 6 FR XL: 10,67kg
    Michelin PS4S: 11,62kg

    Conclusions:
    1) A lot of unsprung weight can be saved by choosing the right tyre brand & model
    2) the choice of tyre is led by the rear one as there are the most differences

    19" versus 20":
    remarks:
    the rear tyre 305 30 20 is actually one size taller and more rumber, comparing to 305 30 19 the "right" tyre would be 305 25 20 (less rubber so less weight). But not interesting for me.
    the front tyre 245 30 20 is also one size wider then the direct comparing one 235 35 19. 235 30 20 shouldn't be used front as LOI is spot on and no reserves here, more chamber then OEM due to coilover and you are above the limit.

    With the right manufacturer tyre setup the 20" ones (being one size wider front and one size taller rear) are lighter then the lightest 19":
    Pirelli P Zero RO 1 in 245/305 30 20 is front 19,34kg and 24.2kg rear, so 43.54 kg or -1.5kg in total lighter compared to the lightest 19" tyre combo one

    a) closest is Michelin PSS in 19" with being 19,92kg front and 25.12kg rear per wheel, so 45.04kg in total.
    b) in 235 30 20 and 305 25 20 I am sure there is another 1-1,5kg possible, so direct compared sizes its between 2,5-3kg less unsprung weight in 20" compared to 19".
    c) the tyre is the most outside part of the wheel so the influence on unsprung and rotational mass is the biggest one on the car! -1kg tyre weight counts more then -1kg wheel weight.
    Last edited by Helldriver; 05-17-2019 at 07:35 AM.
    Notice: We guarantee fast service, no matter how long it takesHidden Content

  2. Remove Advertisements
    Audi R8 Forum
    Advertisements
     

  3. #2
    Senior Member Trev450's Avatar
    Join Date
    Aug 2016
    Location
    South Wales. UK
    Posts
    2,475

    Re: tyre weight, tyre weight saving potential and 20" are lighter then 19" (surprise)

    Very interesting and useful info, Helldriver. Thanks for posting.
    10 V10 Coupe, Ibis, 6MT, Capristo, Carbon Blades, OZ Ultraleggera HLT's, Maxton Splitter.
    Maintained by RE Performance.

    Mitsubishi Evo V1 RS450 Extreme

    Hidden Content

  4. #3
    Member andy bell's Avatar
    Join Date
    Aug 2018
    Posts
    77

    Re: tyre weight, tyre weight saving potential and 20" are lighter then 19" (surprise)

    It is part of the whole picture, we must measure rolling radius (as it effect gearing and acceleration) of each individual set up to properly declare winner here

  5. Remove Advertisements
    Audi R8 Forum
    Advertisements
     

  6. #4
    Senior Member
    Join Date
    Oct 2016
    Location
    switzerland
    Posts
    769

    Re: tyre weight, tyre weight saving potential and 20" are lighter then 19" (surprise)

    Quote Originally Posted by andy bell View Post
    It is part of the whole picture, we must measure rolling radius (as it effect gearing and acceleration) of each individual set up to properly declare winner here
    I expect the winner would be even clearer the 20" if comparing the actual same sizes in rolling radius 235 30 20 and 305 25 20 with 235 35 19 and 305 30 19. Was not asking for that precise data as not of interest for me. Asked for some data just to proof this too, see below.
    Also the flow or rotation forming technology enables the wheel producers to offer 19" and 20" with nearly the same low weight for reasonable pricing and the difference to a real forged lightweight wheel in the same size is around 1-1.5kg per wheel for triple+x cost. So with the right tyre you can even compensate that in 20" but not in 19".

    Done that whole picture for me. The gearing is a bit too short in the frist 3 gears on V8, especially if you modify the engine to 480hp, less curb weight plus soon RWD. With using 305 30 20 I catch 3 bunnies at the same time...lengthen the gearing a bit, having a bit more sidewall rear for more grip and a very slammed look while being on OEM ride height (speed bumps, parking garage...) with a 15mm lowered GT coilover suspension.
    Front to cure understeer and have a matching rolling radius to rear the solution is 255 30 20. With the right tyres I only have a tiny bit more unsprung weight then OEM 19" setup, thats the real surprise.

    Far more interesting is
    - that 19" and 20" setups (tyre+rim) are in general quite even in weight, when choosen right
    - some OEM tyre specs rise or lower the weight signifcantly
    - that a 235 can weight more then a 255
    - how much you can save in unsprung weight just by using the right tyre (brand/model/width).
    Was surprised myself when I got all this data.

    Also interesting and surprising is that I can go far wider with 9x20 and a 255 30 20 tyre and have only a tiny bit more unsprung weight compared to already lightweight OEM doublespoke 8.5x19 with 235 35 19 with the right tyre and wheel setup (that costs 2k). For 6k with OZ supertourismo 20" I could get another 1.5kg front and 1kg rear off with the downside of having a 8.5 front plus a rim load rating of 430kg compared to 700kg now (more stable wheel, not unimportant on bad mountain roads).
    Last edited by Helldriver; 05-17-2019 at 09:42 AM.
    Notice: We guarantee fast service, no matter how long it takesHidden Content

  7. #5
    Senior Member
    Join Date
    Oct 2016
    Location
    switzerland
    Posts
    769

    Re: tyre weight, tyre weight saving potential and 20" are lighter then 19" (surprise)

    just some more data in the direct comparing size 235 30 20 and 305 25 20

    tyre size 235 30 20:
    Conti 6: 10.18kg
    Michelin PS4S: 9.7kg


    tyre size 305 25 20:
    Conti 6: 11,88kg
    Michelin PS4S: 12,19kg

    so a set of Conti 6 is 20,36kg + 23,76kg= 44,12kg
    set of Michelin PS4S is 19.4kg+24,38kg= 43,78kg

    the lightest 19" Michelin PSS were 45,14kg, again heavier by 1.3kg then direct comparing sizes in 20".
    or if you choose wrong and use in 19" the Hankook its a 22kg+27.72kg=49,72kg, means you are +5,94kg heavier then the 20" combo Michelin PS4S or +6.18kg compared to lightest 20" tyre combo Pirelli Zero RO1. Thats the weight saving potential people spend >6000Euro for a set of forged lightweight OZ wheels....
    Again surprise is that the 245 30 20 and 305 30 20 combi is even lighter then the smaller 235 30 20 and 305 25 20. So its not only sidewall size.....
    sometimes wider is lighter and better :-)


    another thing to mention, in 305 25 20 there are no OEM spec tyre avaliable. OEM have their qualified reasons not to use a 25 tyre height in 20"


    To be clear, we are talking here about weight saving only through the choice of tyre of unsprung and rotational mass.
    Unsprung weight you can multiply with factor 4 or 5, means your car is 6.14kgx4 or 5=25-30kg heavier with the wrong 19" tyres, the damping is less precise with less comfort and you have more wear on everything that is affected by damping eg dampers, springs, ball joints....
    rotational mass you can multipy with factor 10, means with the wrong 19" tyres your engine has to speed up 6.14kgx10=61.4kg more weight which results in less HP , torque and more fuel consumption plus higher brake wear as the +60kg have to be stopped too. And +60kg is significant here!!!
    Last edited by Helldriver; 05-17-2019 at 10:11 AM.
    Notice: We guarantee fast service, no matter how long it takesHidden Content

  8. #6
    Member andy bell's Avatar
    Join Date
    Aug 2018
    Posts
    77

    Re: tyre weight, tyre weight saving potential and 20" are lighter then 19" (surprise)

    Somehow you missed important factor of rotational mass distribution from center. More mass further out from center is bad. So your 20 wheel set up might be equal in weight to 19, but having heavier rim barrel further out will diminish any gains from "lighter tire" you might have in 20 size.

  9. #7

    Join Date
    May 2019
    Location
    Madison, WI
    Posts
    54

    Re: tyre weight, tyre weight saving potential and 20" are lighter then 19" (surprise)

    Quote Originally Posted by andy bell View Post
    Somehow you missed important factor of rotational mass distribution from center. More mass further out from center is bad. So your 20 wheel set up might be equal in weight to 19, but having heavier rim barrel further out will diminish any gains from "lighter tire" you might have in 20 size.
    The information on 19's vs 20's on weights and sizes is very helpful. Its just rarely (almost never) the case that a larger diameter wheel is better for performance, handling, steering and ride even at same OD tires.

    So what Andy notes here is correct. Rotating inertia which is referred to here is directly proportional to diameter to the 4th power...20^4/19^4 = 23% greater rotating inertia in simple terms...at the same weight but 1" greater diameter. More complicated than that in taking the whole mass/mass distribution...in which they are not typically for equivalent stiffness. Increasing rotational inertia is quite detrimental to acceleration and deceleration.

    For a 20" wheel to equal a 19" in weight it is likely is not as stiff, which is critical for vehicle dynamics (especially handling and steering).

    Reduction in overall unsprung mass with all else equal is good, but within a small range (and even larger) the suspension can readily be tuned for ride and handling.

    The biggest "pro" for larger wheels typically involves ability to use bigger brakes if they are needed for fade during track running. But there are obvious rotational inertia and weight tradeoffs again depending on brake choices. And then of course many like the bigger wheels for aesthetics.

    So the wheel/tire weight and size information posted here is great, but larger wheels are not a great path for better performance or vehicle dynamics.
    2012 Audi R8 | V10 | Manual | AWE Exhaust | Carbon Blades | Carbon Engine Bay | Tuscan Brown Interior 2009 Buell 1125R | Barker Exhaust and ECM Tune | Michelin Pilot Road3's

    Ahlman Performance LLC | Audi R8 Ohlins Coil-Overs | Chassis Development

  10. #8
    Senior Member DaveL's Avatar
    Join Date
    Mar 2015
    Location
    Fortaleza, Ceará, Brasil.
    Posts
    1,883

    Re: tyre weight, tyre weight saving potential and 20" are lighter then 19" (surprise)

    A very technical answer but how do you justify that they just look good LoL.
    Black/Gold 09 V8 Coupe R-Tronic. Black/Gold 05 Race prep'd Yamaha R1.

  11. #9

    Join Date
    May 2019
    Location
    Madison, WI
    Posts
    54
    LOL...I included that DaveL! Nothing wrong with that...you are just far more likely to go slower than faster!

  12. #10
    Senior Member DaveL's Avatar
    Join Date
    Mar 2015
    Location
    Fortaleza, Ceará, Brasil.
    Posts
    1,883

    Re: tyre weight, tyre weight saving potential and 20" are lighter then 19" (surprise)

    Quote Originally Posted by Scott-AhlmanPerformanceLLC View Post
    LOL...I included that DaveL! Nothing wrong with that...you are just far more likely to go slower than faster!
    If I want to go really fast I take the motorbike out (carbon fibre wheels and Ohlins suspension front/back and steering damper)
    Black/Gold 09 V8 Coupe R-Tronic. Black/Gold 05 Race prep'd Yamaha R1.

  13. Remove Advertisements
    Audi R8 Forum
    Advertisements
     

Page 1 of 2 12 LastLast

Similar Threads

  1. Beautiful 19" Wheels Tires 19 X 8.5" 19 X 11"
    By jbusa95te in forum For Sale - Parts
    Replies: 13
    Last Post: 12-28-2018, 06:17 PM
  2. WANTED: Lighter wheels 19" or 20" in SoCal
    By BlackBear in forum For Sale - Parts
    Replies: 0
    Last Post: 10-08-2016, 09:21 PM
  3. 2017 Audi A5, S5 Debut with More Power, Lighter Weight
    By AutoGuide.com in forum Audi R8 & Site News
    Replies: 0
    Last Post: 06-02-2016, 04:40 PM
  4. 20" adv.1 5.2.1 SL black with MPSS less then 1500 miles
    By Ny04g in forum For Sale - Parts
    Replies: 0
    Last Post: 06-14-2015, 10:22 PM
  5. Replies: 0
    Last Post: 10-12-2014, 04:24 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Powered by vBadvanced CMPS v4.3.0