Tire Diameter vs. ABS How Important???

[TexasBowhunter]

While I was doing some research on tires for the 18" wheels on my street glide I came across an article addressing the ABS braking system and how important it is to maintain the correct diameter of the tires in relation to what was OEM...

from what I understand the OEM diameter is 25.32 on the front and 25.22 on the rear...

So now the question comes up with the other offerings from the various Manufactures tires in which they are offering and the diameter being different and how it will/could affect the ABS braking system...

can the diameter of the tires be changed in the ECM to accommodate this change to correct the systems ABS braking? Is this something I can do or is it HD specific assuming it can be done?

[joe_lyons]

The problem becomes when there is a difference in sensor speed from front to rear or vice versa.

[PC_Hater]

What an interesting question!
There has to be enough leeway in the sytem to cope with tyre wear and under inflated or over inflated tyres.
I do know that when I switched from the 16" front tyre to an Avon 18" front tyre the diameter was almost exactly the same - to 0.1". And that was good because my 99 FLTRI is the last year of the front wheel driven speedo.

In short, it will _probably_ be OK.

[TexasBowhunter]

The problem becomes when there is a difference in sensor speed from front to rear or vice versa.

So what you are saying may be something to take into consideration...
Just how much can the front and back be different?
how much problem would be with a 25.5 front and a 24.8 rear? total 7/10's difference...
or front 26.25 and rear 25.39 almost an inch difference
paul

[PC_Hater]

What is the tread depth on a new official HD rear tyre?
Let's say it is 0.25", that can't be too far off correct.
That means a very worn tyre will have a diameter that is half an inch lees than when it was new.
Have that with a new front tyre and you have a half inch difference that the system has to be able to cope with.
Or more to the point, there _will_ be a speed between the front and rear difference caused by the different diameters of a new and a worn tyre.

Until we know any better I would choose the 25.5 front and 24.8 rear.
From the above we know 0.5" of that could be just tyre wear. The extra 2/10s to make it 7/10s could easily be made up of under inflation and over inflation and the system has to be able to work with that.