Yup, except if you put really big wheels on the front it ruin your fuel economy 'coz you'll always be going up hill

 

I remember on my old 356 Porsche the speedo/odo was driven off the left front wheel. On other RWD cars I've owned the pick up must have been on the rear end because on several occasions I remember pegging the speedo when I spun the tires, especially in the rain.

 

I have a January 2001 Build S2000.

The car was radar checked at 115 Km/h
and the speedo was reading 116 km/h.

Its very close, but as usual is a fraction
conservative for legal and safety reasons.

-Kupe.

 

If you start putting different size fronts and backs on the car, your ABS computer will freak out, and the light will come on the dash telling you so.

 

what happens if you used smaller profile tires ?

 

Thanks for the replies, Low-S2000 and AusS2000. Makes sense that acceleration would decrease with larger circumference. Anyone know how much? If the top speed were rev limited, top speed would increase a bit. But I understand the top speed is drag limited, which means (I think) that it wouldn't increase and might actually decrease. AusS2000, are there any pics you can point me to that show that larger wheel and lower profile tire on an S2000, like yours? Thanks again.

 

The link in my sig will take you to a page about the ROH Adrenalin. At the bottom of the page is a link to a series of pictures in large and small format.

One of the better ones is:

 

Quote:

Originally posted by AusS2000
Yep. If you use a wheel/tyre combo with a different rolling circumference your speedo will be wrong.

To calculate the error go to Tyre Calculator

Just as an exercise, enter the stock tyre sizes and the tyres used at the link in my sig.

AusS2000 - Do you know if there is any practical way to modify anything, say in the speedo connection to the drivetrain, or anything else to offset the impact of using larger wheels/tires, so that the speedo stays reasonably accurate? [/QUOTE]

They sell gear sets at your local speedo tuner shop. I had it done when I had bling bling wheels on my prelude, those were the days!! [/B][/QUOTE]

I'm not 100% certain about this as I don't have an S2k workshop manual but it would be my expectation that there are no gears for the speedo drive. Essentially there is a magnet glued to the drive shaft which passes a fixed sensor every revolution of the drive shaft. The detected signal is then passed to the electronic speedo which converts the readout into pretty red lights for us all to gauge our speed by.

If you have a bicycle computer it is essentially the same principle and you would know that there is a mode setting which allows you to input the distance travelled in one wheel revolution (on more basic models it is just wheel diameter). I am fairly sure that the same facility would exist for our S2k speedo computers but I don't know where you are going to get that factory setting info from.

If you can get it, however, then as you can see, it would be fairly easy to reset the speedo for accurate reading of any size tyre wheel combo.