its a given fact that a 17" wheel with the correct tyre has the same rolling diameter as a 15" cyclone with the right tyre,
if you put a 17" wheel on that weighed exactly the same as a 15" with the same offset then you would notice a huge difference using two identical spec tyres in the different profiles
At the end of the day a straight wheel swap using the right size wont alter and geometry such as tracking, castor or camber,
however if you were to lower your car and then whack some different wheels on and think your going to be on rails think again, doing this you have just introduced many many problems in one change, such as:
*Unsprung weight
* you've now altered your castor and camber's working derogatory values due to a different ride height
*correct offset
*vehicle track width (remember an ET15 on a 6j wheel would provide a radically different track to an ET15 on a 7.5j wheel)
*rear weight and corner weight will now all be different too
Just 2% cross-weight can provide a detrimental effect into what you think the car is doing,
I've had my car on the scales to try and achieve a better balance, purely because i have access to them, remember 20 litres of fuel is 20kilos of rear weight, weight percentage that's now not hanging over the front wheels.
The only real good way to ever know if the wheels solely make a difference is to make sure all these things are the same to achieve a fair ground to test on
if anybody wants to drop me a PM of anything to do with set-up and scaling up etc go for it.
If there's enough interest I wouldn't mind even writing a technical set-up and check list etc to put on the forum in a section if the mod's wanted?
if you put a 17" wheel on that weighed exactly the same as a 15" with the same offset then you would notice a huge difference using two identical spec tyres in the different profiles
At the end of the day a straight wheel swap using the right size wont alter and geometry such as tracking, castor or camber,
however if you were to lower your car and then whack some different wheels on and think your going to be on rails think again, doing this you have just introduced many many problems in one change, such as:
*Unsprung weight
* you've now altered your castor and camber's working derogatory values due to a different ride height
*correct offset
*vehicle track width (remember an ET15 on a 6j wheel would provide a radically different track to an ET15 on a 7.5j wheel)
*rear weight and corner weight will now all be different too
Just 2% cross-weight can provide a detrimental effect into what you think the car is doing,
I've had my car on the scales to try and achieve a better balance, purely because i have access to them, remember 20 litres of fuel is 20kilos of rear weight, weight percentage that's now not hanging over the front wheels.
The only real good way to ever know if the wheels solely make a difference is to make sure all these things are the same to achieve a fair ground to test on
if anybody wants to drop me a PM of anything to do with set-up and scaling up etc go for it.
If there's enough interest I wouldn't mind even writing a technical set-up and check list etc to put on the forum in a section if the mod's wanted?