How does the size of wheels affect performance?

Smaller wheels = faster acceleration?

Larger wheels = better turning?

Smaller wheels ( smaller diameter ) less traction, Larger diameter wheels, more traction.
Lower profile tyres, better cornering, less comfort.
High profile tyres, cornering not so good, more comfort, better traction.

Don't forget to consider tyre width and air pressure when you are considering traction. (Low pressure (below 26psi) = grip eg Drag cars, high pressure (38psi+) = manouverability and braking.

I can't wait to fit bridgestone eager 235/55 15's to my 15x7 el ghia rims, it's just these current bob jane allrounders (205's ) are so damn good!

I thought they were only available in the SF330 ( 50 series ) or SF340 ( 60 series ).
I have the SF340's. A mate of mine had SF330's on his fairlane and they made the speedo out a fair way. I found the SF340's to make the speedo more accurate ( according to a mates GPS ).

 

 

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You're right it is a 60 profile. The s340 comes in 225 and 235 widths. The 235 width affects the speedo but i believe the 225 is pretty much equal to stock. I do 500km of highway driving a week so i'm hoping the 235 will improve my economy as a wider diameter will mean the engine is revving lower at high speed.

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Diameter refers to the side of a tyre - ie the 55 part of a 255.
Smaller diameter does not = less traction.
Larger diameter does not = more traction.

Whats a very common drag size rim? 15x10. Small diameter isnt it? Its only 15", though when fitted with an appropriate tyre you have far more grip than a more commmon aftermarket wheel of say, 18"x8".

A 14"x8" 12 slot fitted with a 235 has far more traction than a 15"x6" steelie fitted with a 205 doesnt it, yet which one has a larger diameter?

If you get too large a rim and too small a sidewall handling and grip become adversely effected.
Why do V8 Supercars only run a 17" If what you said was true they should be running like 20"s or 22"s yeh?


To answer the initial question - if you're referring to the force required to rotate the wheel initially, it depends entirely on the rim design, as I had a set of 17s that even when fitted with a tyre, were lighter than a set of 15s, no tyre, I have.
If you're talking about just in general, a 14" rim with a 245 will give faster quarter times than a 18" rim with a 245, just because of the give in the sidewall, and the more effective lower pressures are in smaller rims.

If you want your car to handle well, and have a massive increase in grip all round (in a commonly available tyre), you cant go past a 17 or 18x8 rim fitted with a 245.
You get good acceleration because of the reasonable width combined with a reasonable sidewall height, and good handling because of the width, and reasonable sidewall height. A little bit of sidewall flex under cornering is good, you dont want a rock hard tyre with no give.







If you do that it is wise to install a speedo corrector, unless of course you like speeding tickets? Though the difference in rpms (therefore economy) will be stuff all.
If you want better hwy economy install a higher diff ratio - 3.08