Weight of Wheels
06-14-2004, 12:30 AM
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This is not directly related to E60.
I used to have a set of ACS wheels for my current 540i. But over the years, they got all scratched up and I eventually went back to the original BMW wheels that came with the 540. When I changed back to the original, I noticed a BIG difference in fuel consumption. (280km per tank vs 230km per tank) I assume the ACS are much lighter.
So now that my 545 is coming, I am once again looking at wheels. My 545 comes with Type 123 wheels, I will probably use it for a while, but if I do get new wheels, I want to take weight into account. Does anyone know if there's a list of specs on the BMW wheels, including WEIGHT?
I used to have a set of ACS wheels for my current 540i. But over the years, they got all scratched up and I eventually went back to the original BMW wheels that came with the 540. When I changed back to the original, I noticed a BIG difference in fuel consumption. (280km per tank vs 230km per tank) I assume the ACS are much lighter.
So now that my 545 is coming, I am once again looking at wheels. My 545 comes with Type 123 wheels, I will probably use it for a while, but if I do get new wheels, I want to take weight into account. Does anyone know if there's a list of specs on the BMW wheels, including WEIGHT?
06-14-2004, 01:24 AM
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I know its a simplistic question but were the ACS wheels the same rolling circumference as the BMW ones, were the tyres the same width?
if so, surely unsprung weight wouldn't have this huge effect on mileage (But it would have an effect on handling being unsprung weight)
DD
if so, surely unsprung weight wouldn't have this huge effect on mileage (But it would have an effect on handling being unsprung weight)
DD
06-14-2004, 02:23 AM
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Hey Dr.
To be honest, I do not know exactly.
The ACS were 'Type II', and were 17in. My stock 540 wheels are 16in. The ACS were probably slightly bigger overall... so if my logic is correct, the 16in should really have better fuel consumption (lighter to turn).
I was surprised too, but nothing else was changed.
To be honest, I do not know exactly.
The ACS were 'Type II', and were 17in. My stock 540 wheels are 16in. The ACS were probably slightly bigger overall... so if my logic is correct, the 16in should really have better fuel consumption (lighter to turn).
I was surprised too, but nothing else was changed.
06-14-2004, 03:34 AM
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Just a quick question on this, but did you do the consumption checks manually or was it from the cars trip computer? If you used the car's computer, it could also be the a difference in tire circumference might have changed the calculations so that the real consumption was not being measured correctly. Just a thought????
06-14-2004, 06:05 AM
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Originally Posted by gdavis' date='Jun 14 2004, 07:34 AM
Just a quick question on this, but did you do the consumption checks manually or was it from the cars trip computer? If you used the car's computer, it could also be the a difference in tire circumference might have changed the calculations so that the real consumption was not being measured correctly. Just a thought????
If there was any error due to circumference, wouldn't it be present with the odometer too or would it be so minor that it wouldn't affect anything?
06-14-2004, 06:19 AM
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Yes indeed
overall smaller circumference = speedo would read too fast and milage would over-read giving the impression of better mileage
other way round if overall larger circumference, more chance of a speeding ticket!
"but officer, the speedo only showed 70"
overall smaller circumference = speedo would read too fast and milage would over-read giving the impression of better mileage
other way round if overall larger circumference, more chance of a speeding ticket!
"but officer, the speedo only showed 70"
06-14-2004, 09:49 AM
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Different wheel size and weight of wheels might make some difference to gas mileage but I suspect that lowfriction-tires or the difference between different brands makes a bigger difference.
I have kept an extensive statistic on my present wheels for an E46 and the difference is around 5% in MPG just between two brands (both low-friction) and same size. Ironically it?s the winter type that has the best mileage in my case (Bridgestone) compared to the (Michelin) summer tyres.
I?ve also noted that AC in 18-23 degrees C outside makes almost no difference to MPG same with heating (+5 to -10 C outside). Rainy weather gives also a 5% increase (more than wind actually) in consumption. Speed makes of course the biggest difference (10-15% plus going 140 instead of 110) with city erraticness in driving coming second. Loading the car up with 2 extra adults and 100 kg of packaging actually changed MPG less than changing tyres.
(all figures from a 320D(00 model) with careful records for 200000 km since new. Calibrated distance and fuel capacity giving a very good average since new of 0,5litres diesel/10 km in mixed driving - official BMW figure for that model actually 5.7 litres/100km)
Hoping for a similar experience with my new E61.
best
objetti
I have kept an extensive statistic on my present wheels for an E46 and the difference is around 5% in MPG just between two brands (both low-friction) and same size. Ironically it?s the winter type that has the best mileage in my case (Bridgestone) compared to the (Michelin) summer tyres.
I?ve also noted that AC in 18-23 degrees C outside makes almost no difference to MPG same with heating (+5 to -10 C outside). Rainy weather gives also a 5% increase (more than wind actually) in consumption. Speed makes of course the biggest difference (10-15% plus going 140 instead of 110) with city erraticness in driving coming second. Loading the car up with 2 extra adults and 100 kg of packaging actually changed MPG less than changing tyres.
(all figures from a 320D(00 model) with careful records for 200000 km since new. Calibrated distance and fuel capacity giving a very good average since new of 0,5litres diesel/10 km in mixed driving - official BMW figure for that model actually 5.7 litres/100km)
Hoping for a similar experience with my new E61.
best
objetti
06-14-2004, 02:47 PM
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objeckt, nice measurements. I am curious to see how the BMW OBC calculated gas mileage compared to your own, or is it the car data only you were reporting? I too have suspected tire model and brand were important. It is worthwhile to know it amounted to 5% difference. I think it would help many of the forum readers to know the identity of the two tires you compared. Even better, your tire size and working pressures as well.
06-14-2004, 09:12 PM
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Looks like the 'blame' has turned to tires, instead of the weight of the wheels.
Well, let me put that straight. I used the same tires on both sets of wheels.
I used Potenza S03 Pole Position in both cases.
The overall size sounds like a more possible cause. I am just using the odometer to do these 'readings'. Nothing scientific. However, the difference is fuel consumption is approx 18%. There's NO WAY the overall circumferences of the wheels differ as much as 18%! That's a lot!
is it really possible that ACS wheels are just VERY light?
Well, let me put that straight. I used the same tires on both sets of wheels.
I used Potenza S03 Pole Position in both cases.
The overall size sounds like a more possible cause. I am just using the odometer to do these 'readings'. Nothing scientific. However, the difference is fuel consumption is approx 18%. There's NO WAY the overall circumferences of the wheels differ as much as 18%! That's a lot!
is it really possible that ACS wheels are just VERY light?