Wheel Upgrade to 20s...Need advice

VCuomo · 05-01-2011, 04:04 PM

Quote:

Originally Posted by 6MT

So the extra 1"-2" between the axle and the ground doesn't slightly raise the bottom of the car as well? What does it do, just compress the springs extra? Seriously, please explain.

LunaZ · 05-01-2011, 04:08 PM

Quote:

Originally Posted by VCuomo

So the extra 1"-2" between the axle and the ground doesn't slightly raise the bottom of the car as well? What does it do, just compress the springs extra? Seriously, please explain.

When the diameter of the wheel is increased, the aspect ratio of the tire is reduced. The aspect ratio is a number that describes the height of the tire's sidewall relative to the width of the tire.
The goal is to end up with the outer diameter of the tire being the same as what it came with from the factory regardless of what diameter rim you put on the car.

daisuke149 · 05-01-2011, 04:12 PM

Quote:

Originally Posted by VCuomo

So the extra 1"-2" between the axle and the ground doesn't slightly raise the bottom of the car as well? What does it do, just compress the springs extra? Seriously, please explain.

Quote:

Originally Posted by LunaZ

When the diameter of the wheel is increased, the aspect ratio of the tire is reduced. The aspect ratio is a number that describes the height of the tire's sidewall relative to the width of the tire.
The goal is to end up with the outer diameter of the tire being the same as what it came with from the factory regardless of what diameter rim you put on the car.

in simpler words, where your adding 1-2" of wheel, your removing 1-2" of tire. if you go with a large side wall, while still going up 1-2" of wheel, then yes it will increase ground clearance, throw off your speedometer/odometer, lower your acceleration, throw off the handling, etc. Generally a bad idea so best deal is always try to make sure that Wheel + tire = same overall diameter as the original wheel + tire. Gotta look at them as a package and not individually.

VCuomo · 05-01-2011, 04:16 PM

Quote:

Originally Posted by LunaZ

When the diameter of the wheel is increased, the aspect ratio of the tire is reduced. The aspect ratio is a number that describes the height of the tire's sidewall relative to the width of the tire.
The goal is to end up with the outer diameter of the tire being the same as what it came with from the factory regardless of what diameter rim you put on the car.

Quote:

Originally Posted by daisuke149

in simpler words, where your adding 1-2" of wheel, your removing 1-2" of tire. if you go with a large side wall, while still going up 1-2" of wheel, then yes it will increase ground clearance, throw off your speedometer/odometer, lower your acceleration, throw off the handling, etc. Generally a bad idea so best deal is always try to make sure that Wheel + tire = same overall diameter as the original wheel + tire. Gotta look at them as a package and not individually.

Gotcha, but actually I was assuming that only the rim size was being increased. So it is assumed that you always decrease tire profile (aspect ratio) to match the original wheel diameter when you increase the rim diameter? I've seen a lot cars where it appears that the tire profile wasn't decreased enough to make up the increase in rim diameter.

daisuke149 · 05-01-2011, 04:20 PM

Quote:

Originally Posted by VCuomo

Gotcha, but actually I was assuming that only the rim size was being increased - is it assumed that you always decrease tire profile (aspect ratio) when you increase the rim diameter?

generally yes. Some rare occasions people will change the side profile as well but its generally for a specific purpose and they do it on purpose vs just happened.

VCuomo · 05-01-2011, 04:23 PM

Quote:

Originally Posted by daisuke149

generally yes. Some rare occasions people will change the side profile as well but its generally for a specific purpose and they do it on purpose vs just happened.

Thanks for the info guys! The facepalm and wtf emoticons weren't nearly as informative!

ImportConvert · 05-01-2011, 05:52 PM

Quote:

Originally Posted by VCuomo

So the extra 1"-2" between the axle and the ground doesn't slightly raise the bottom of the car as well? What does it do, just compress the springs extra? Seriously, please explain.

Bigger rim=shorter sidewall. That way all these people driving donk'ed out Z's don't exactly LOOK like they gave up all that traction, braking, and ride-quality.

daisuke149 · 05-01-2011, 05:57 PM

Quote:

Originally Posted by ImportConvert

Bigger rim=shorter sidewall. That way all these people driving donk'ed out Z's don't exactly LOOK like they gave up all that traction, braking, and ride-quality.

because wheel size is the only thing that determiens those. Not the make/model of tire, the suspension modifications, or any brake mods. Just the wheels.

in that case is 19" the universal best grip/braking/ride quality wheel? Or is it any 18" wheel?

P.S do explain how someone going from base 18's with advan sports to maybe a 20" wider wheel with better tires is "giving up braking/traction"

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