First time Exedra Max rear tyre

[motolink]

Can you help me here, since putting on the Bridgestone 255 rear tyre the ABS light comes on after riding about 15 kms, I can stop turn the ignition off restart and ride but the the light will come on in 15 km.

Sorry, the size is 240/ 55

 

[TriumPhil]

Herman, 30 psi is a dangerously low pressure for that tire and I would definitely not recommend regular riding on that rear tire below 36 lbs. For most normal sized humans 38-42 lbs is the sweet zone for that tire. If it's a softer ride ye seek, then experiment with different shocks - not with your tire inflation.

motolink, if you are a "normal" sized human (175-225, let's say) I'd recommend 38-40 lbs up front and 40-42lbs in the rear tire. Experiment adding or losing a pound at a time but one tire at a time, preferably starting with the rear pressure.

 

[Pete]

Can you help me here, since putting on the Bridgestone 255 rear tyre the ABS light comes on after riding about 15 kms, I can stop turn the ignition off restart and ride but the the light will come on in 15 km.

Check the perforated ABS disk that's bolted to the rim. It's aluminium and will bend easily if knocked during tyre fitting. If it's been buckled slightly the reader won't pick up the rotation speed.
This happened to mine so I removed and flattened the plate to fix the problem.

 

[Pete]

Check the perforated ABS disk that's bolted to the rim. It's aluminium and will bend easily if knocked during tyre fitting. If it's been buckled slightly the reader won't pick up the rotation speed.
This happened to mine so I removed and flattened the plate to fix the problem.

Actually I think it's metal not aluminium (just looks like it) but it bends easily

 

[motolink]

Thanks , I will check it.

 

[1olbull]

Can you help me here, since putting on the Bridgestone 255 rear tyre the ABS light comes on after riding about 15 kms, I can stop turn the ignition off restart and ride but the the light will come on in 15 km.

Don't know this Stone 255. Is it a CT?
Anyway, tis the circumference ratio front to rear is what the ECU monitors.
Use the tire aspect ratio and the wheel size to calculate the diameter then Pi x Diameter.
Once you get over about a 8% ratio difference you risk faulting the ECU and ABS.

Example -
The OEM Metzelers have a front circumference of 83.09" and a rear of 79.95"
Difference is +3.14" and 3.14/ 83.09 (front) = +3.8% ratio

The Avon Cobra front is 140/75R17 with a 79.3" circumference.
The Exedra Max rear is 240/55R16 with a 82.9" circumference.
The circumference difference is -3.6". A -3.6/79.3 (front) = -4.5% ratio.

The OEM circumference ratio (front to rear) of +3.8% and the 140/75R17 front with a 240/55E16 Exedra Max rear circumference ratio (front to rear) of -4.5% have a difference of 8.3% (-4.5 + 3.8 = 8.3).
The 130/80R17

I ran a 130/80R17 up front (79.13" circumference) with the Exedra Max rear (82.9" circumference).
This provided a -4.8% ratio and a 8.6% difference (-4.8 + 3.8 = 8.6%) and faulted the ECU ABS.

So then a ratio difference of 8.3% worked fine, but a ratio difference of 8.6% faulted the ABS.

Now if you run the 130/80R17 with a 79.13" circumference up front with the OEM Metzeler rear 240/50R16 with a 79.95" circumference, you would have a circumference difference of -.82" and a ratio of -1%. This provides a ratio difference of just 4.8" (-1& + 3.8%) and likely would not fault the ABS.
I have NOT done this and DO NOT recommend a 130 front on a Roadster as it can drag the peg rails, which I have done . . . and crashed.
HTH

 

[Joesmoe]

That DOES help. How does one find the tire circumference one is considering ?

 

[1olbull]

That DOES help. How does one find the tire circumference one is considering ?

First you need the aspect ratio like 240/55R/16.
55% of 240mm = 132mm side wall. 132 x .03937 = 5.2 inches.
5.2" x 2 + 16" (wheel dia) = 26.4" diameter.
26.4 x pi = 82.9" circumference

 

[Steel]

That DOES help. How does one find the tire circumference one is considering ?

Or go here and put both tires in.

Tire Size Calculator - Discount Tire Direct

 

[TriumPhil]

Don't know this Stone 255. Is it a CT?
Anyway, tis the circumference ratio front to rear is what the ECU monitors.
Use the tire aspect ratio and the wheel size to calculate the diameter then Pi x Diameter.
Once you get over a 4.3% ratio difference you risk faulting the ECU and ABS.

Example - the Exedra Max 240/55R16 is 82.9" circumference.
The Avon Cobra 140/75R17 is 79.3" circumference.
The circumference difference is 3.6". 3.6/82.9 = 4.3% ratio which is within the ECU fault ratio.
I ran a 130/80R17 up front (79.13" cir) which provided a 4.6% ratio and faulted the ECU ABS.
Now if you keep the OEM Metzeler rear 240/50R16 with a 79.95" circumference you would likely not fault the ABS with a 130 due to only a 1% ratio. I have NOT done this and DO NOT recommend a 130 front on a Roadster as it can drag the peg rails, which I have done . . . and crashed.
HTH

Well done, Steve!

I just wanted to add that the B'stone Ex Max seems to have the best circumference size for correcting the nearly 3.5% speedometer deviation on earlier (pre- '09, I think) models.