i plan on having the dealer re-calibrate my speedo since im running tires 3" taller than stock. i called and they said i need to get the RPM's for them to be able to program it. i asked if they could just program in the tire size, they said they couldnt. anyone know where i could get RPM calculations for my size tire and rear? appreciate the help.

 

Go to the website of the "brand" tire manufacturer that you have installed.
All the ones I have seen list the revs per mile on their tire spec. charts

 

yea but on bfg's website for the size tire it says 45 mph= 801 rpms, alittle low you think.

 

I don't know what size tires you have,but the TOYO TIRE site
lists a 285 75R 17 AT tire at 614 revs per mile
I am guessing at 3" taller you have 315's so 801 seems high
should be more like 601 I would think.
But I am not an expert on tires.

Call a local BFG dealer and ask them.

Opps just saw in your Sig. that you have 315's

 

tire specs for bfgs here...........
http://www.tirerack.com/tires/Spec.j...rrain+T%2FA+KO

Bob

 

601 it is...

 

Don't confuse Revolutions per MILE, RPM with revolutions per MINUTE, RPM.

RPM means Revolutions Per Minute (and it's already plural), not RPMs.

Speedo pinion factor needs tire Revolutions per MILE.

When you go over size 285 it is not listed in the DRB tool that the dealers have. They must choose "other" in the list and go by revs per MILE.

Not RPM, but revs per mile.


John

 

according to tirerack that is revs per mile, 601.

 

This is the post I was refering to.

John

 

That dealer is BS'ing you or don't know how to do it. I had my '05 done a couple of months ago at my dealer. I gave them the rev per mile that the Toyo web site gave for the 325's (596). The diesel tech told me they have their own calculations and didn't need the rpm's. He re-programmed it w/ 600 rpm and it is dead on.

 

just got back and gave them the number off BFG's website, 601. tech doing it was going to look on that website anyway he said- so it saved him some time.

 

I was just at the dealer to get my speedo recalibrated for the new 285/70/17 BFG T/A KOs that I had installed last week. They were having all sorts of problems trying to figure out what to do. So after an hour they told me to come back later in the week and/or just leave the truck for the day to try and figure it out. The guy showed me the computer and the only sizes they had were 245 and 265 or "other" nothing about 285. Should I take it back to them or see another dealer?

Thanks,
John

 

by the time the dealer gets it figued out, you could have bought a smarty, got more power, changed tire sizes and had a bunch of fun!

 

What they were telling you holds true for 06 and newer only.When you enter other you are on the right trackTell him to stop fearing the drb and check out all the menues

Bob

 

As I said in my earlier post, "other" is what you want. Then enter the revolutions per mile and you're done.

John