gqii4you

I am thinking about getting the Dronnel's like canren's but am afriad I am gonna loose a lot of my power. I like the gs400 cause of the power and speed and I tend to race a lot but I want the look of the 20's. What do you guys think I should do?

ARB

I am curious about this too, anyone have any info? Also how much more do chrome GS400 17's weigh than the alluminum alloys? I heard 17's were the best size for straight line performance(like 1/4 mile)

Thanks ARB

dipstick

I don't have much experience with the Lexus GS (one month) but maybe I can give you some info to think about. The wheel size will affect performance because of (1) tire O.D., (2) weight of the wheel and tire, and (3) grip of the contact patch. Most of the difference will be low speed torque related. Torque is rotational force times the distance (radius) to the force, in pount-feet. As the wheel diameter increases, the force (lbs) where the rubber meets the road decreases, providing less force, and slower accelleration. So for every 1/2" you increase the tire O.D., you will reduce the accellerating force about 2%, similar to reducing the final drive ratio of the transmission from 3.27 to 3.20. The added weight of the larger wheel/tire combo will use up torque and power equal to the added weight times the radius to the center of rotational mass (lost torque), times rpm for lost HP. 4 pounds added at 9" radius = 2.77 lb-ft of torque and .36 HP at 4000 rpm . Not a lot. For overall performance and handling, the 17" or 18" will be better than larger. There is an excellent study of plus tire sizes in the Feb. 1999 issue of Road & Track, tested on BMW 540i with sport pkg. If you can't find it, I can scan it and email to you. Good luck - this is an interesting decision.

SecPole14

OT: Hey Dipstick,

Maybe we can try to find some other CL members in SC and get a meet together sometime. I've been waiting forever to find some CL members living in SC...

Manaray

I'd be willing to do a run with someone who has stock wheels (but they'll need a Injen intake and an APEX WS exhaust to make it 100% fair)...I've been curious myself.

With my 20" HRE's, I haven't really noticed a slow down. What I do know is that my GS on 20's (with the stock intake and APEX WS exhaust) absolutely spanks my stock SC400 with no mercy whatsoever.

clivej

Hi guys,
you will lose a lot, do a searce ,ther was a post approx.3mths ago about this,two guys with gs4's, both had either 16s or 17s.One guy bought 20's and they raced, 20's lost by about a car length (not positive) ,do a search ,check it out.
clive

LOTC

From a start it start you will be a bit slower,but on the roll it should be about the same speed.

itsallgood

In my experience when I was trying to clock my car in the 1/4 mile...I ran with both the 20's and the 17's...inconclusion with the 20's I lost about 3/4 of a second...

Aloha

JAC JZS

So your saying a stock GS400(which does 14.5-14.6 in the 1/4 mile) will do 15.25-15.35 with 20's on...

lex400sc

How much do stock GS wheels weigh? I know my cast aluminum 16's weigh 41 pounds each with a tire and the spare is 54 pounds. I'd imagine the stock chrome 17s will weigh more than mine. If you can find a 20 that is light (no chrome), I think the reduction in rotational mass will more than compensate for the loss of rear wheel torque.

dipstick

Right, Lex400sc -- if gqii4you is careful and has the money for forged wheels, he could come out with the same or less weight and no loss in torque or power on that account.

gsstud

definitely slows your car down!! but looks so good though!!!

MrSypher

I just put 20's on my GS300 and I notice it is alot slower now... Before I could get it up to 140mph with no problem and now I don't think my car can even do it now..... So far all I can do is about 130mph..

ARB

Right, plus most people that go for 19 or 20 inch+ wheels don't go for anything lightweight they just go for show, which there is nothing wrong with, it all depends on what you want. Plus a lightweight 17 inch wheel will always be lighter than a lightweight 19 inch wheel(i.e. 17 inch O.Z. Superleggera vs. 19 inch O.Z. Superleggera) SSR makes pretty lightweight wheels too

S300

I agree