I bought my 03 Cummins QC at the end of Feb and so far have not been impressed with the stock tires after 5500 miles of hummin the cummins. On my 97 Cummins I have 285/75R16 BFG AT's and loved the performance and handling. Has anybody put BFG AT's on there 03 I was thinking of 315/70R17's but wondered if they will fit or am I gonna have to lift the truck and also wondered if anyone found a way to fix the speedo for the large tires yet on these new computers.<br>Nathan<br>

 

[quote author=BigBlueCummins03 link=board=20;threadid=14579;start=0#136752 date=1052553335]
I bought my 03 Cummins QC at the end of Feb and so far have not been impressed with the stock tires after 5500 miles of hummin the cummins. On my 97 Cummins I have 285/75R16 BFG AT's and loved the performance and handling. Has anybody put BFG AT's on there 03 I was thinking of 315/70R17's but wondered if they will fit or am I gonna have to lift the truck and also wondered if anyone found a way to fix the speedo for the large tires yet on these new computers.

Nathan

[/quote]

If your truck is a 4x4 the 315/70/17 will fit just fine. I've got them on mine, and it's stock height. If I have any rub at all, it's only slight, and only at full lock. I don't really think that mine rubs, but that's the only case I can see it rubbing. Unless, of course, you're doing some serious off-roading. Then it might happen.

As far as correction, I know there is a post somewhere on this board recently where someone got the speedo correction from Superlift and put it on his truck. The wiring was a bit different, but he got it to work.

EDIT -- Here is the link to the Super Lift speedo correction install.

 

I have also installed a set of BFG AT's 315/70/17 - on the stock rims. I drove it around a week before putting on the 2&quot; leveling kit yet had no rubbing during that time. There's more room under these 3rd gen trucks than the older models.

I don't chirp the tires so easily now and really like the smoother, softer ride. I run the new tires at 47 PSI front and 33 PSI rear (empty). And, I keep the old tires in the bed - takes the edge off the HD suspension and gives me a bit of extra weight in the rear for snow/mud travel.

There's about a 9% circumference difference between my old tires and the new. That's close enough to 10% - making it easy for me to mentally figure. If the speedo says 50, I'm going close to 55. If the speedo says 60, I'm going close to 66. Etc..........

Man, the power of these new trucks is amazing. In 6th with 3.73 diffs I know I could pull another gear - even with 35&quot; tires. With these new tires, at 2000 RPM I'm doing 75 MPH (corrected). Sweet.

Best to y'all
Bill