265's and antilock brakes

[403turbo]

I just replaced my firestone "steelslicks" with BFG T/A KO's in 265x75x16. I live in NY next to the worlds largest snow machine (lake Ontario) and have noticed that my antilock brakes are not as sensitive as they were with the 245's. I searched for old threads about this because I'm sure it has been discussed, but I couldn't find any that talked about this problem.

Is this normal and OK....or should I be looking to have something in the computer adjusted to compensate for the size change?

Antilocks still work when I stand on them but just don't feel the same.....it snows everyday here so I have plenty of chances to use the antilocks.

By the way, I used to be in 4 wheel drive everyday just to get to work.....with the BFG's.............. I DON'T NEED NO STINKING 4 WHEEL DRIVE!!

Well at least til it gets really nasty

Thanks for any insight to this problem

[DmaxMaverick]

Could it be that the new rubber is getting better traction?

The ABS senses loss of traction. More traction = less ABS.

I have about 30K on 285's with no calibration. Never felt like the ABS was week.

If the wheels don't lock up, don't worry about it.

[403turbo]

Yeah, I guess that makes a lot of sense...

Sometimes you just have to hear someone else say it... :rolleyes:


Thanks

[Black Dog]

Ditto what he said, it is because you are getting better traction. BFG A/Ts get great traction on snowy and icy roads. Waaaaaay better than a worn out set of stock Firestones.

[JimWilson]

Some of the programmers (like Hypertech, Superchips and Predator) can compensate for different tire sizes, but going up 1 size shouldn't screw up the ABS. Heck, I have 285's and I don't think it's a problem, and unfortunately I had a very good chance to test them just last week when some drunken scumb@g pulled out in front of me and I had to slam on the brakes. I was on the pedal so hard the seatbelt locked on me, but the truck never skid for even a second.

[ryeguy]

The dealer cannot compensate for a different tire size with the diesel trucks (and likely others) when it comes to the speedo. But he can compensate for the different tire size for the ABS. I had mine done, and noticed a difference right away.

--Rob

[KompressorMan]

403turbo,
I'm with you, when I installed 265 Michelin tires I immediately noticed a decrease in braking action. What I attributed it to was a difference in the moment from the axle due to a larger circumference. It does take more effort to stop now.
Herb

[Bass_on_tap]

Ryeguy, what's involved in the ABS compensation? Was it something you paid the dealer to do and if so, how much? Thanks Dave

[afp]

My truck came with the 2455s. I immediately swapped them out for 265s, then took it to the dealer for a speedo recalibration. I had to argue with the dealer about there indeed being a speedo calibration for 265s, because that is one of the optional tire sizes from the factory. He reluctantly took the truck in, and lo and behold thewe WAS a speedo calibration for the 265 tire size. My speedo reads dead on.

Blaine

[TBC]

I changed my tires at 22,750 miles because the tread was down to l/8 in. It was very disappointing that the tires would not last any longer than that. I had Michelin A/S LT265-75R16E tires put on it. The truck sit noticeably taller but does not appear to have any trans shift problems. I compared the speedo with my GPS and the speedo is about 1.5-2.0 MPH slower than the GPS. I am going to take it to the dealer for a recal and see what happens there. Truck rides much better and than with the Firestone Steeltex.

[ryeguy]

I didn't ask for any recalibration. I complained about the transmission not shifting right or something (forget off-hand). I wanted the updated transmission programming.

Dropped off the truck, came back, and they said they warranteed it, put in the new software, reset everything, and determined that was likely because of the wrong size tire, and they had corrected it. No charge, sir, thank you for your business.

Nope, my handy-dandy GPS told me that the speedo was still out by some 4%. But the brakes behaved a lot differently. I noticed it as soon as I got out of the parking lot, actually. This confirms what I've read here, that:
- presently the software for the diesels cannot handle a change in tire size regarding the speedo, shifting, etc.;
- but the software for the ABS can in fact be reset for different tire sizes.
Odd, eh. But I've got 265's, a speedo that is out by 4%, and great braking.

--Rob

[ 01-26-2003: Message edited by: ryeguy ]</p>