ABS Warning Light "On"

[The Melmaan]

Hello Guys,
I recently changed my front tires to new tires but what I did was to get tires that are narrower than the old tires. I have a set of 245x45x17, the rear tires are getting on the bald side but the front tires still got a lot of life on them. If any of you have wider and bigger tire, you will notice that they are heavy and kinda hard to steer. So, what I did was (kinda stupid) to buy newer tires off EBay but the size is 205x40x17. I was thinking that the smaller front end will make steering easier which it did. Now I ended up with another problem, the ABS warning light turned ON. I search the web and found the following:
ABS WARNING LIGHT COMES ON
MODELS AFFECTED: All with ABS
FAULT: ABS warning light comes on intermittently. Normal troubleshooting procedures find no defect.
CAUSE: If cars have recently had two new tires, or snow tires put on. Sometimes when the car is driven
over 50 MPH.
SOLUTION: Check all four tires on the car, make sure they are the same brand, style, and size. Check if
any of the new tires have substantially more tread than the rest. These differences may cause enough
variance in rolling diameters to confuse the ABS control unit, which intern gives a false signal to the ABS
warning light
The questions are:
HOW BAD IS THIS?
DO I NEED TO CHANGE TIRES AGAIN?
WILL THE COMPUTER / SENSOR BREAKDOWN?
WILL IT DO DAMAGE TO OTHER COMPONENTS?

Need all the help that I can get.

Thanks,
The Melmaan

[Kalevera]

I mean....it could be a tire issue, but I think it's more likely that one of the sensors is shot. The fronts like to go -- I just replaced one of mine after a trip through southern ohio. Is there any consistency in when the light turns on? Sometimes it'll be a directional fault, you turn the steering wheel to the left a few times after starting to drive and the light pops on while turning left, which might pinpoint things to the left front wheel sensor. EDIT: sometimes the coding wheels will just get clogged up with gunk -- it's unlikely on the E34 because the dust shields cover them pretty well.

The thing to do to confirm what's going on is get it on diagnostics. A '93 ABS control should be integrated with the rest of the controller area network (I know most early E34s require a special BMW plug in diagnostic module -- someone might be able to confirm ye or ne that the '93 is integrated with OBD).

best, whit

[jjw]

It's your tire size. The new ones just too small. The ABS is confused, it's reading too much of speed difference between the front and rear. You will have to match the right size front and rear and the problem will go away.

[mattyb]

i heard of this some time ago. advice i heard was that in the event of abs being required it will not engage bcause of alert status. dunno really if its the case or not.

[brodee]

I would also guess that it's your tire size. The 205/40 is more than an inch smaller diameter than the 245/45 that you are running on the back.

[Javier]

9.48 % difference in radius, so will be the rpm difference.

Javier

[The Melmaan]

Thanks guys,
I think that I have to change the tire back to the 245x45x17