Hey guys, it's time to buy new tires and I had a couple Qs.

I did a true manual swap from my 02 TL-P to an 03 CL-S6. From the factory wheel specs, it seems the CL-S6 has a bigger tire diameter.

I was debating whether to use the CL-S6 rims, or the original TL-P rims. Does the car's speedometer and odometer work from the ECU or the Speed sensor?

In other words: because I am using the CL-S6 ECU, has my speedo been a little off? Or is that not affected because I am still using the stock speed sensor?

 

So your original TL-P rims are 16" in diameter...... not 17" as the CL-S ?

The CL-S models had a lower profile sidewall and wider tread tire on the larger diameter rim when compared to the TL-P. The key is to match up the overall running diameter of the tire,.... not the rim to keep the speedo correct. I'm unsure if it's the speed sensor or the ECU that determines this ?

 

So the TL-P has the rim diameter of 16", or 406.4mm. The stock tire has a sidewall height of 123mm. The total diameter is then 652.4mm.

The CL-S has the rim diameter of 17", or 431.8mm. The stock tire has a shorter sidewall height of 107.5mm. The total diameter is then 646.8mm.

So the Type S diameter is roughly 5.6mm Smaller than the Base model. This translates to about 0.69" of circumference on the wheel.

My question is, does the ECU calculate this knowing the stock size, or does the Speed Sensor know this?

 

I have 18"rims with 235-40-18 tires, with my tl-p gauge cluster it was off a couple mph. I swapped in a tl-s cluster and now my speedometer is almost dead on, I don't know why but it is. I would put the 17" cls rims on mostly for asteric reasons.

 

Ooo, good point. It's probably just in the cluster's calibration. Duh. Good thing I have the CL-S6 cluster.

Thanks.

 

Hmmmm, Oh yeah man, that all makes total sense now !

The speed sensors are more than likely a common element whose only practical purpose is to read the wheel's revolutions and then transferring that input to the ECU, in turn enabling it to then calculate the values for the output which is viewed on the dash speedo display.

So, turn that TL-P into a TL-CS6.....rims and all !!!