Acceleration between 17 inch and 18

[RedGull]

As above just put on 18’s and it accelerates so much slower! Thought it might but not this much! Does not bother me as I go for looks over anything else! Be interesting to know the time difference

 

[merc85]

What car is it???

 

[RedGull]

C250 204

 

[whitenemesis]

An enlightening read
How Does Wheel Size Affect Performance?

 

[RedGull]

Interesting! Would say as well can hear the engine a little bit more on take off! But again it does not bother me, but would say the 7 spoke come as standard on these cars as well as split spoke 17’s which I had, have to say the 17’s are better overall but I like the look of 7 spoke!!

 

[DSM10000]

If you increase the wheel diameter but reduce the aspect ratio of the tyre so that the rolling radius of the wheel / tyre system is the same regardless of the wheel being 17" or 19" then nothing has changed in the system, the wheel and tyre need to be considered together as an entity.

The larger the tyre in terms of footprint etc the greater the frictional loses .

 

[WOODYTHEWISE]

That was very interesting

 

[RedGull]

Was going to sell the 17’s but might just keep! For what I don’t know!!

 

[whitenemesis]

Was going to sell the 17’s but might just keep! For what I don’t know!!

Winter tyres?

 

[RedGull]

Might be a good idea! Don’t know which is standard size for these cars as seen both sizes on them?

 

[Gazwould]

Very interesting .

I only knew from a unsprung mass point of view .

Certainly noticed the difference from 16 to 17 on another car but then the diameter increased more than the math because tyre manufacturers don't keep to the sizes .

Felt like a higher gearing effect .

It's all a bit of the three, torque loss , unsprung mass and gearing .

18" absolute max for me .

19"+ , some people don't notice , some people don't feel...

 

[RedGull]

Gaz, get some 17’s!! The difference is massive! But I know! the 7 spoke look so good!

 

[190]

Even when there is no gearing change, heavier wheels take more power to accelerate and braking will suffer too for the same reason. Theses are double effects as total vehicle weight goes up and rotational inertia goes up.

 

[Gazwould]

Gaz, get some 17’s!! The difference is massive! But I know! the 7 spoke look so good!

Lol , too much love for the Ronal's .

Might add even more unsprung mass in the form of 322 × 32 .

 

[DSM10000]

Even when there is no gearing change, heavier wheels take more power to accelerate and braking will suffer too for the same reason. Theses are double effects as total vehicle weight goes up and rotational inertia goes up.

But two wheels of the same diameter but made of different materials can each have different mass so it is not just wheel diameter (or more correctly wheel and tyre diameter combined) that can affect inertia.

 

[Bellow]

It is where the mass is distributed relative to the centre that most affects rotational (polar) inertia.

 

[RedGull]

Would say at low speed and from start off fuel would go up, but on long fastish runs fuel would come down??

 

[190]

Would say at low speed and from start off fuel would go up, but on long fastish runs fuel would come down??

Heavier wheels would increase fuel consumption but this is a relatively small effect and would be hardly noticeable.

If overall wheel diameter is the same and therefor no change to gearing I can see no possible reason why fuel usage would go down on longer runs just because the wheel are heavier.

 

[RedGull]

Larger wheels at higher speeds lower revs = less fuel,heavier wheels would make no difference at all imho, my 17’s as a split spoke have 12 spokes so could argue that they are heavier! But that I don’t know, smaller wheels at higher speed more revsmust again = more fuel?

 

[Scoops1972]

Might be a good idea! Don’t know which is standard size for these cars as seen both sizes on them?

My Dunlop Sport Maxx RT2 summer tyres are 225/40/18 Front and 255/35/18 Rear.

My Michelin Alpin PA4 winter tyres get swapped onto the same rims and are 225/40/18 Front AND Rear.

The Michelin site states that although these aren't the same sizes as original spec, they are the approved size for winter use.

Check the Michelin site out to see what size is recommended for your old 17" rims?