I like the fact that the back of the seville is a lil higher but
I just don't like the huge gap between the rear wheel and the fender.
Because my 98 STS sitts very high in the rear I would like to mount bigger tires - but only in the rear. At the moment my tires have the stock overal-diameter (26.8 inches) but I would like to mount tires with 1.20 inch more overal diameter (28 inches).
This would mean that my rear wheels are bigger than my front wheels. How would this affect the ride? Will I even notice this?
Re: Bigger wheels but only in the rear = good idea ?
I had a 93 and I dont recall the gap being more extreme or noticable.
Its a given that the back end in general was high. But I dont recall the gap in the wheel wells being of any concern.
It may be possible you have a problem with your leveling/suspension.
If you put different size tires on the back the revolutions are different. (RPM)
The ABS and Traction Control for all tires work together on one system. Its set up knowing that all tires are the same size. And making the same revolutions as per the parameters of its programming. If you put different size tires on the back, then the revolutions per minute will be different for those tires.
The system will constantly be thinking that something is slipping, skidding, or spinning, out of the range of the parameters that are normal.
So it will be constantly kicking in to compensate.
Re: Bigger wheels but only in the rear = good idea ?
Traction control and ABS get signals based on tire RPM and throttle imput. So, the computer sees one RPM for the front and a different RPM for the rear. Too bad its not the 70's anymore! You can adjust the rear level ride sensor to lower or raise the static height in the rear and its free!
Re: Bigger wheels but only in the rear = good idea ?
Quote:
Originally Posted by carnut
Traction control and ABS get signals based on tire RPM and throttle imput. So, the computer sees one RPM for the front and a different RPM for the rear. Too bad its not the 70's anymore! You can adjust the rear level ride sensor to lower or raise the static height in the rear and its free!
Like I wrote above I do not want to lower the the static height in the rear.
I like this muscle car look - so I wanted to keep the rear end high but fill out the gap between rear wheel and fender.
Is it possible to recalibrate the system for two different wheeldiameters?
Re: Bigger wheels but only in the rear = good idea ?
If you put bigger tires on the back they would be spinning slower than the smaller diameter front wheels..... The easiest way to do it would be to splice the wires from the front wheels so that the EBTCM sees the data from the front wheels as the data for the rear wheels as well... Of course your Traction control and ABS would not work properly after doing that though.
I'm not sure about how to recalibrate the system... A Tech-I or a Tech-II scan tool may possibly be able to recalibrate it. But really I have no idea about it. Dealerships Have the Tech-I and Tech-II tools.
Re: Bigger wheels but only in the rear = good idea ?
Quote:
Originally Posted by mike.nite
Is it possible to recalibrate the system for two different wheeldiameters?
Given the complexity of the systems involved (ABS + TC + Stabilitrak) if you have ~$10,000 in equipment and masters degrees in physics and computer science, access to a test track and a few months to devote to nothing else it could probably be done. For us mere mortals - no. The algorithms that correlate wheel speed to suspension control and ABS engagement were all designed with the assumption that all four wheels are the same diameter. To me, trying to do this is substantially more complex than trying to hack the PCM to play with the engine power curve.
