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Vekke · 07-07-2019, 08:22 AM

Before changing tires I have installed a kammback spoiler which helped about 5%. So I have already seen 5.5-5.6 l/100km @ 100 km/h figures. Then I had 225/60R16 Hakkapeliitta R winter tires which had 4mm thread depth left.https://ecomodder.com/forum/tool-aer...ToStep=40-65-1

At the moment struggling still struggling with tires. Bougth 205/75R16 113/111S Nokian Hakka C2 tires, but fuel consumption increased 0,5 liters :/. Their figures were rolling resistance C, rain grip C and noise 70db. Rolling resistance in between (RRC6,8-8,0) Migth be due to these are new so rolling resistance is 20% higher than with those very worn winter tires. Also winter tires RRC is measured at. Here calculated at rrc 8.0. I also lose 2% on smaller diameter, which you need to add on top of that. https://ecomodder.com/forum/tool-aer...ToStep=40-65-1 Its a little shame as these tires were really nice to drive even with 5 bar pressures.

Now trying to find a better solution. and found this Continental VanContact Eco 235/65 R16C 115/113R they have A, A and 71 db C2 tyre class. Which means their rollign resistance RRC is under 5,5!. Note that passenger tire (c1 tyre) A level means only under 6,5 RRC. So these are 15% better in rolling resistance than the A level tires for passenger cars C1 tyres. Their load index 115 = 1215kg means they can carry a big load. This also means they are tested with heavy loads on the RRC tests, which should lead better rolling characteristics on the touareg where one corner weigths about 550kg.

Well now the fuel consumption starts to look much better, at least on paper

. 5.3 liters should be on reach @ 100 km/h speed. https://ecomodder.com/forum/tool-aer...ToStep=40-65-1 With the C tires you can also put much higher tire pressures as max sidewall is 5,2 bars usually.

EDIT: In reality these new Continental VanContact Eco 235/65 R16C 115/113R tires are only slightly better than the previous Nokians. Fuel consumption about 5,9-6,0 liters at 100 km/h speed

One option to test will also be 265/50R19 Nokian WR SUV 3, which is also AA tire, but its tested on winter temps so rrc is under 6.5, but actually it is lower on summer. These I try to find used ones to get even lower rollign resistance figures. 10 celsius change in tire temperature means 20% reduction in rolling resistance.

As you can see from those calculations the heavier the car the bigger effect on rolling resistance has on your fuel consumption. On tiny cars the aerodynamics play maybe bigger role what I have learned so far.

07-07-2019, 08:22 AM	#54 (permalink)
Vekke Mechanical engineer Join Date: Jan 2009 Location: Kitee (Finland) Posts: 1,275 Siitin - '98 Seat Cordoba Vario 90 day: 58.56 mpg (US) VW Lupo 3L --> 2L - '00 VolksWagen Lupo 3L Diesel 90 day: 104.94 mpg (US) A8 luxury fuel sipper - '97 Audi A8 1.2 TDI 6 speed manual 90 day: 64.64 mpg (US) Audi A4B6 Avant Niistäjä - '02 Audi A4b6 1.9tdi 96kW 3L 90 day: 54.57 mpg (US) Tourekki - '04 VW Touareg 2.5TDI R5 6 speed manual 90 day: 32.98 mpg (US) A2 1.4TDI - '03 Audi A2 1.4 TDI 90 day: 45.68 mpg (US) A2 1.4 LPG - '02 Audi A2 1.4 (75hp) 90 day: 24.67 mpg (US) Thanks: 273 Thanked 843 Times in 416 Posts	Before changing tires I have installed a kammback spoiler which helped about 5%. So I have already seen 5.5-5.6 l/100km @ 100 km/h figures. Then I had 225/60R16 Hakkapeliitta R winter tires which had 4mm thread depth left.https://ecomodder.com/forum/tool-aer...ToStep=40-65-1 At the moment struggling still struggling with tires. Bougth 205/75R16 113/111S Nokian Hakka C2 tires, but fuel consumption increased 0,5 liters :/. Their figures were rolling resistance C, rain grip C and noise 70db. Rolling resistance in between (RRC6,8-8,0) Migth be due to these are new so rolling resistance is 20% higher than with those very worn winter tires. Also winter tires RRC is measured at. Here calculated at rrc 8.0. I also lose 2% on smaller diameter, which you need to add on top of that. https://ecomodder.com/forum/tool-aer...ToStep=40-65-1 Its a little shame as these tires were really nice to drive even with 5 bar pressures. Now trying to find a better solution. and found this Continental VanContact Eco 235/65 R16C 115/113R they have A, A and 71 db C2 tyre class. Which means their rollign resistance RRC is under 5,5!. Note that passenger tire (c1 tyre) A level means only under 6,5 RRC. So these are 15% better in rolling resistance than the A level tires for passenger cars C1 tyres. Their load index 115 = 1215kg means they can carry a big load. This also means they are tested with heavy loads on the RRC tests, which should lead better rolling characteristics on the touareg where one corner weigths about 550kg. Well now the fuel consumption starts to look much better, at least on paper . 5.3 liters should be on reach @ 100 km/h speed. https://ecomodder.com/forum/tool-aer...ToStep=40-65-1 With the C tires you can also put much higher tire pressures as max sidewall is 5,2 bars usually. EDIT: In reality these new Continental VanContact Eco 235/65 R16C 115/113R tires are only slightly better than the previous Nokians. Fuel consumption about 5,9-6,0 liters at 100 km/h speed One option to test will also be 265/50R19 Nokian WR SUV 3, which is also AA tire, but its tested on winter temps so rrc is under 6.5, but actually it is lower on summer. These I try to find used ones to get even lower rollign resistance figures. 10 celsius change in tire temperature means 20% reduction in rolling resistance. As you can see from those calculations the heavier the car the bigger effect on rolling resistance has on your fuel consumption. On tiny cars the aerodynamics play maybe bigger role what I have learned so far. __________________ https://www.linkedin.com/in/vesatiainen/ Vesa Tiainen innovation engineer and automotive enthusiast Last edited by Vekke; 08-14-2019 at 04:41 PM..