Effects of upsizing your wheels and tires

P

powerontap

Senior member
 Montreal
Interesting test with +/- of upsizing your wheels and tires:

http://www.caranddriver.com/features/10q1/effects_of_upsized_wheels_and_tires_tested-tech_dept
 
That's a really good article that does a fair job of being scientific.

Big = slower acceleration, lower fuel economy and on the 19's even less corner grip than 18's

Show or go seems to sum it up.
 
That would explain on the new Z4 why in most car mag pics and TV tests the cars had the 18" wheel package! :wink:

The 19" looks good, but sticking with my 18" I think! :D
 
I'm glad I'm on 18" wheels - those 19" CSL are obviously a psychological advantage and for 'show' only :poke:

How close would the acceleration & fuel economy figures have been had they kept the wheel & tyre weight standard across the test. Also keeping the tyre width uniform would probably have negated some of the improvement in lateral grip.
 
So, really we should all be like Woots and driving around on 16"s? :wink:

Oh no, he's going to love this thread...
 
I'd say just as important is staying with the size wheel the car came on. Manufacturers spend a lot of money coming up with packages that work well together.
 
Smokin said:
I'd say just as important is staying with the size wheel the car came on. Manufacturers spend a lot of money coming up with packages that work well together.
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And it has nothing to do with saving money, or inducing the customer to upgrade the wheels from 'factory fit' little ones :evil:
 
a11y said:
So, really we should all be like Woots and driving around on 16"s? :wink:

Oh no, he's going to love this thread...
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Ah, but in that case, anything gained by the 16" wheels is taken away from by having a 4 pot motor! :P :fuelfire:
 
Breaker said:
a11y said:
So, really we should all be like Woots and driving around on 16"s? :wink:

Oh no, he's going to love this thread...
Click to expand...

Ah, but in that case, anything gained by the 16" wheels is taken away from by having a 4 pot motor! :P :fuelfire:
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"Best" of both worlds then when I've got my winter wheels fitted - 3.0i 6-pot and 16"s :D

4484178241_b11c8fa175_b.jpg
 
hmm

tested on a golf mind you

the zeds are already put on wide and bigger wheels ,oem up to 18 inch
so when upgrading to 19 inch the diferance is not too big i guess

maybe the fuel consumption goes up but hey in holland we have an old wisdom saying "who wants to be pretty must suffer"

so im getting 19 inch soon!!
 
to be honest, i would rather have a car enhanced to my personal preference as i couldnt really give a shiny shi* about loosing 0.1 second to 60 and im also happy to lose a few mpg, both of which i havent noticed since upgrading to 19" alloys.

who is going to notice such slight differences anyway.
 
easty027 said:
to be honest, i would rather have a car enhanced to my personal preference as i couldnt really give a shiny shi* about loosing 0.1 second to 60 and im also happy to lose a few mpg, both of which i havent noticed since upgrading to 19" alloys.

who is going to notice such slight differences anyway.
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x2 :thumbsup: Would not go back myself, the car looks amazing on 19'' IMO.
 
powerontap said:
easty027 said:
to be honest, i would rather have a car enhanced to my personal preference as i couldnt really give a shiny shi* about loosing 0.1 second to 60 and im also happy to lose a few mpg, both of which i havent noticed since upgrading to 19" alloys.

who is going to notice such slight differences anyway.
Click to expand...

x2 :thumbsup: Would not go back myself, the car looks amazing on 19'' IMO.
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x3 :thumbsup:
 
sandere85 said:
the zeds are already put on wide and bigger wheels ,oem up to 18 inch
so when upgrading to 19 inch the diferance is not too big i guess
Click to expand...

but the whole point is the outside diameter doesn't change usually.....yes the wheels are bigger but the tyre profile is lower to compensate in most cases....just enter the relative tyre/wheel sizes for 16", 18" and 19" here....

http://www.kouki.co.uk/utilities/visual-tyre-size-calculator
 
On a Z4 the diameter of the tire should be right at 25 inches. For an "M" is should be right at 26 inches. So for whatever rim you are using the diameter of the tire you are using should get really close to the original.

Here is another link that has both inches & metric.

http://www.miata.net/garage/tirecalc.html
 
I think we're missing the point here. The article is not talking about rolling diameter of the combo of wheel and tyre. It's a given that that should correct, else overall gearing, speedo, etc. will be off. This is more about the effect of a larger wheel and matching lower profile tyre.

Putting the mass of the wheel further from the centre of rotation and often coupled with even wider rims creates a decrease in performance and mpg. I agree that nobody driving a performance car give a rats ass about 0.1 of anything in normal road conditions. Most interesting was that grip decreased on larger rims beyond what seemed an optimal 18"

Aside track use I think choice of wheel style, looks, comfort, etc. are the real considerations.
 
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