BADGS400

hey guys, I am about to put my new 20's on and was wondering how this will efect the odometer and speedometer, will it read fast or slow or neither, will my car think that it is going more miles than it is(rack up miles more overall) or thinks it going not as far(less miles than stock) i know i didnt explain this very good, im sorry but any help would be great

BTW: you guys with 20s and stock or ltune or trd springs how much did it make the ride feel worse?(using 35 series if it matters)

Lvangundy

not too tire saavy, but I think changing the tire size only makes a difference with the speedo

BADGS400

ivan are you sure about this, i could have swore i read it did something else too?!?!

I know lots of you have 20's what the ride like ??

Jmai22

it all depends on the diameter of the wheel. you notice that most 20inch rims have lower profile tires right?? well thats partly because to keep the stock shape of the wheel as much as possible and also for rubbing purposes.

if your wheel diamter is bigger it should make your speedometer read slower than you are driving lower miles. imagine if you had tires that were only 10 inches in diameter. that means your wheels will have to spin more in order to cover the same distance a wheel that is 20 inch in diameter hope that helped

itsallgood

Well as for the ride, its alittle stiffer than the stock 17's. As for road noise it depends on the tire brand.

On my car the mile per hour did change. If the speedo shows 60 mph, I'm actually going 64 mph. That's what my friends lazer gun registered when we were testing a new lazer jammer.

Aloha

Manaray

itsallgood - Hey, nice SC setup in your GS! I'm jealous! (but don't worry, I'm not going to key your car!)...how does that Laser Jammer work? Does it really jam the signals or is it 50/50 or is just a crock?

BadGS400- Ok, let's cover the easy stuff...your braking will be affected due the increase in rotational mass/force. You'll notice longer braking distances...a big brake kit or a Supra TT brake kit (ask SUPRATRD about these) will solve that problem in a jiffy.

As for "ride quality", this is VERY subjective (at least to determine LEVEL...as there is definitely an decrease in ride quality). One person's **** might read the same car completely differently than another's...PSI also matters...running my 20's at 42PSI vs 36PSI makes a WORLD of difference to my butt...however, the different between a stock 17" setup and my 20" setup, FOR ME, it isn't all that bad. Of course, I now have all sorts of "stiffening" items added to my GS so the ride quality in my car wouldn't be quite the same as riding in a GS that just has a set of 20's with the L-Tuned setup...I have coilovers, TRD Sways, and all sorts of TOM'S bracing...

Now for the more complicated shiat...let me expand on what Jmai and Itsallgood posted...

With a 20" setup, you're speedo will definitely be off. It'll be slower. That's because a "standard" 20" tire setup has a overall diameter that's larger than even a "standard" 19" set-up...and definitely more than a 16"/17"/18" setup (unless you're buying some seriously high profile tires for those smaller wheels)

The reason why this happens is because the Speedo/Odo reads revolutions of your wheel to determine speed/distance. If you increase the overall diameter, in one revolution, you're stock (235/45-17) tires travels 25.3" where as a 245/35-20 travels 26.8"

...so 25.3/26.8 = 0.944

Now 0.944 x 64 MPH = 60.4 MPH (which was proven by Itsallgood's laser gun)

Now the stock tires do 796 revolutions per mile...whereas the 20 (in the size spec'd above) does 754 revs per mile...This means that your car's ODO will show LESS miles that it actually has (though it'll only be off by 5.6%)...that's because your speedo/odo thinks you've traveled only 60 miles (at a true 60MPH) in one hour but in reality, you've traveled 64 miles (at a true 60MPH)

Does that make sense? I hope I explained it clearly...

alexus

iTrader: (1)

um.. it doesn't feel lik luxury car anymore.. it feels bumby and you got to go around any catch basen, otherwise you can damage your rims.. they look phat.. i dont know about speed or miles.. though

LXOGOOD

"The Wheel GOD has spoken".... nuff said!

enginyr

If your scared.....You can always trade your 20's for my 19's