So, I'm looking around for the best deal on 265/75/16's. A guy I work with says, " go see my buddy at ....." So off I go. I say to this bonehead, "I've got 245's and want to go to 265's." "What year?" he asks. I say "'96 Dodge 3/4 ton diesel." He says, "Oh boy. You better talk to Dodge about doing that. I know somebody with a '94 Chevy that changed tire size and his mileage went from 20 to 9. It competely screwed up the computer in the truck." I'm thinking, what did the guy put on, go-kart tires? So I say, "I don't have electronic fuel injection." He tells me, "that doesn't matter. The computer counts every rotation the tires make." I'm thinking to myself, why am I arguing trying to give this moron $800? So I thanked him for the advice and walked out. (Totally out of character but I'm trying to turn over a new leaf )The thing is, should I tell my co-worker about his hero tireguy? He's sort of a Know-it-all, I'm better-than you type. I got the new leaf thing happening, but....... Hmmm, mind's made up. I'm going to tell him in front of some other people. I can always be a nice guy starting tomorrow. ;D

 

I don't think he was too far out of line. There may be some basis there for the gasser. He just doesn't know your truck as well as you. He wasn't trying to force something on you like some. If his price is acceptable, just tell him you won't hold him liable for the electronics.

 

You're probably right that it might throw a EFI gas truck out a bit. But this guy's shop was full of semi tractor tires so he should have a basic knowledge of diesel trucks. Everywhere else I went didn't question it. Not even Costco, who has a notoriously bad rep for not putting non-stock tire sizes on, had a problem with this swap.

I'm finding more and more businesses that have seemed to forget that "the customer is always right." I've had certain diesel shops, non that advertise here, tell me I need to buy bigger injectors because I'm wrecking my pump with too much pressure from my fuel plate. Same place told me that you can't buy parts for a pre-heater a week after I bought them from Cummins. They wanted to sell and install a new one for $300 + labor. I really feel sorry for the people that rely on outfits like this to be straight up with them.

As far as the tire guy goes, I wouldn't spend my hard earned cash at his place if he was $50 cheaper per tire.

OK, I'm getting off the soapbox now.......

 

Something to keep in mind.
Increasing tire size (in theory) will lower fuel mileage around town (albeit, only a little) as the engine will have to work a little harder to get the larger tires to start rolling in city traffic.
(again, this is in theory and probably only comes into play if your change from a small tire to a really large tire).

Also, going from a small tire to a larger tire will reduce how many miles will show up on the trip meter between fillups.
The larger tires turn slower than the smaller tires... this give the effect of traveling fewer miles on the same tank of fuel.
This can be fixed by having your speedometer recallibrated.

Perhaps this is what that shop owner was hearing about.
Rich

 

I told him I realized that my speedo and odometer would be out (calculated about 4%) but he was adamant that it would wreak havoc on everything.

It's no big deal, I'll buy elsewhere. Just thought it was a funny story about trying to get someone to take my money.