does anyone know if the speedometer gear in the transmission can be changed when using oversized tires on a GS400? I know that some of you have 20's with 245/35's and we all must know that it throws off the speedometer.

Anyone know when you can get the new gear from?

 

I have no clue,, But that question was floating around in my head too.....

 

Factory diameters:

215/60-16's: 664mm
225/55-16's: 654mm
234/45-17's: 643mm

Notice there's a 3% diff between the smallest and largest even for FACTORY tires.

245/35-20's diameter: 680mm

That's 2.4% bigger than the biggest above (215/60-16).

So which is right? Who the frig knows.

 

I wonder if this explenation works when you get a ticket, LOL.

 

Right.....

 

so are you guys trying to say that putting 20's on your car will change your actual speed A LOT, i mean like more than like 4 or 5 mph...


drew

 

the speedometer is set to the 17" wheel size, i'll tell yo utaht right now....

so you'll be 5.2% off

 

Unless I'm mistaken (God knows THAT happens often enough), the speedometer and odometer are not mechanically driven from the trans. So no gearing to replace.

 

when you are really going 66mph your speed will only say 60 mph.........so those tickets may be higher than you thought...........maybe you can explain that to the officer........lol


"yes officer, i'm sorry, but i'm rolling on these oversized Dubs and you know how that could effect my speedometer, so i really didn't know how fast i was going. it only said 100, not 106mph....", LOL


i just don't see that working...........unless your female.

 

are you saying that it recalibrates or there is no way to adjust it by a gear? If so, does anyone know how that is corrected on the GS?

 

You can't correct it. And it's no big deal. 5% at 60mph is 3mph. Big whoop.

 

I guess for thoughs of you who said that they went 120, with Bits calculation you were only going 114 but 120 sounds better

Aloha

 

A slight bit off topic, but the discussion is here ..

The US rules are that the speedo should be with-in +-5%.
The European standard is it can't be -%, so BMW and Benz usually show higher speed on the display than the rate of travel.

Salim

 

jbbnet, I didn't mean to imply that the speedo would re-calibrate. It has no way of knowing the circumference of the wheel/tire combo.

itsallgood, that's incorrect. Since the overall diameter is larger for the dubs (680mm vs 643mm), your indicated speed will be lower than your true speed, so you'll actually be doing 126. I suspect that the finer points of that calculation will be lost on the officer that pulls you over.

 

Man I used to do 5 over the speed limit......and you telling now I have to slow down to one under the speed limit....