ABS Light stays on with 130/70R-17 front tire

OK this is PURE speculation but.....

Under EU law a mfr MUST allow for a plus or minus 3% difference in tyre size as the law allows you to use tyres that have a circumference of plus or minus 3% against the original spec. Why? because even within a given tyre size there are differences between mfr's and tread depth makes a bigger difference than you might think.

You might be on to something there Chris, although I dont think it will be anything to do with the EU +/-3% malarkey. More likely to be the ECU working within a programmed tolerance between front and rear wheels. Going to a wide variation between the two is outside the range and the ABS throws a wobbly.

Using a 240/55 and 140/?? may have the same effect - who's going to try it first. :confused:
 
Not that it is an option, but I wonder if the ABS would just turn off or might it do some erratic embarrassing pulses?

Perhaps Triumph would offer a clearer understanding of what's in play?
 
You might be on to something there Chris, although I dont think it will be anything to do with the EU +/-3% malarkey. More likely to be the ECU working within a programmed tolerance between front and rear wheels. Going to a wide variation between the two is outside the range and the ABS throws a wobbly.

Using a 240/55 and 140/?? may have the same effect - who's going to try it first. :confused:


I stated this once before; but, I have used up two 140 front tires. I NEVER had an ABS light or fault in all the 12.000 total miles. As to the rear 240, are not both front and rear ABS systems independent?

Really would like some GURU to 'splain what is happening here and IF the 130 is REALLY causing the fault.
Best Regards,
1olbull
 
Well, if the powers that be here (Shawn) would stop acting like a 2 year old and allow ART (IMFASTTOO), to post here, you'd have your answer and possibly even a solution. I ain't holding my breath though, as it seems that a certain someone is suffering from a long-term temper tantrum.

As for a 140 tire selection, I would strongly endorse the Michelin Commander II, although I have since matriculated to the even better B'stone Exedra Max 130... 'tis a beautiful thing!
 
I stated this once before; but, I have used up two 140 front tires. I NEVER had an ABS light or fault in all the 12.000 total miles. As to the rear 240, are not both front and rear ABS systems independent?

Really would like some GURU to 'splain what is happening here and IF the 130 is REALLY causing the fault.

The issue comes because electronic ABS compares front and rear rotational speeds as part of the algorithm of predicting loss of traction. If the wheel actually stops - ABS is not doing it's job correctly. If it detects what it sees as a potential loss it backs off the pressure a bit on one wheel or another to avoid locking. The ratio of rotational speeds is hard coded.

MOST modern ABS systems will simply let wheels lock if the compare function fails - but some BMWS were known to default to NO BRAKES if the compare function failed.

A 130/70R17 is spinning 9,4% faster than a 150/80R17 at any given speed

Add that a 240/55R16 is spinning 3,6% slower than a 240/50R16 at any give speed.

So the ABS sees a 13% difference in rotational speed Front to Rear than expected/programmed. This is interpreted as a fault.

It's a GUESS - OK - I said GUESS. It probably puts up with 10% difference tops. And EU law menns it has to accept a minimum of 6%.

a 140/75R17 and 240/55R16 is a total of 8,3% (4.7 faster front and 3.6 slower rear)

Simple maths.
 
The issue comes because electronic ABS compares front and rear rotational speeds as part of the algorithm of predicting loss of traction. If the wheel actually stops - ABS is not doing it's job correctly. If it detects what it sees as a potential loss it backs off the pressure a bit on one wheel or another to avoid locking. The ratio of rotational speeds is hard coded.

MOST modern ABS systems will simply let wheels lock if the compare function fails - but some BMWS were known to default to NO BRAKES if the compare function failed.

A 130/70R17 is spinning 9,4% faster than a 150/80R17 at any given speed

Add that a 240/55R16 is spinning 3,6% slower than a 240/50R16 at any give speed.

So the ABS sees a 13% difference in rotational speed Front to Rear than expected/programmed. This is interpreted as a fault.

It's a GUESS - OK - I said GUESS. It probably puts up with 10% difference tops. And EU law menns it has to accept a minimum of 6%.

a 140/75R17 and 240/55R16 is a total of 8,3% (4.7 faster front and 3.6 slower rear)

Simple maths.


barbagris,
Good post and thanks for all your effort. You have brought forth some very interesting concepts that ring very plausible to me.

Now I must break out my own **** calculator and try to find a tire combination that falls within that 10% then go see if it works out.
Best Regards,
1olbull
PS: I must ask - what the heck is a barbagris???????? :D
 
I have tried the smaller front tires and the handling improvement at low speeds is apparent. What I have also found is, the accentuated maneuverability is also apparent at higher speeds which I do not enjoy at all. The bike is rock solid at one ton plus speeds with a stock tire. Not so with the smaller. I am going back to stock size on the front even though it robs hp.
 
It means "Grey Beard" in Spanish.

Have a Tyre calculator. Tire Size Calculator - Compare Tire Sizes


Barba Gris,
Thanks for the post. I was faked out not understanding it is actually two separate words. I have been referred to as senior barba and meester whiskers many times while visiting Jalisco, MX. Over the years I have grown older in appearance and last year some pendejo at the beach called me Santa Clause! :eek::roll::sick:

Anyway - you know your $hit about ABS, Amigo! I verified with a senior sport bike mechanic that what you had surmised about the wheel circumference ratios affecting the red warning light was SPOT ON. He also told me the ABS remains in effect and shall perform properly in spite of the warning light. Bottom line is I ordered up a 130 Excedra Max for my front, which shall take me on my ride to CA in a week. So, I shall indeed learn if I get a ABS warning light or not. If I do, I'll be igging it. :D
Best Regards,
1olbull
 
I have tried the smaller front tires and the handling improvement at low speeds is apparent. What I have also found is, the accentuated maneuverability is also apparent at higher speeds which I do not enjoy at all. The bike is rock solid at one ton plus speeds with a stock tire. Not so with the smaller. I am going back to stock size on the front even though it robs hp.


I respectfully disagree here, STRIPES.
On three occasions I recorded 128, 126 & 131 mph rips on my GPS and speedo on my recent cross country ride. I had two different brand 140s (Michelin and Dunlop) on the front and experienced nothing different than when the stock 150 was mounted. Also, the bike was loaded up pretty good for the long trip.
Best Regards,
1olbull
 
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