What would the pros and cons be to changing my tire size on my 2013 GMC 2500HD diesel from an LT265/70R18 to an LT275/70R18? I'm looking at doing this due to cost only. I can get a very good price on the LT275 Goodyear tire. I know it will change my speedometer reading vs actual speed. I'm wondering about any hidden issues I haven't thought of. Thanks in advance!

My stock size is 275/70R18 and one thing I like about them is they seem to give me a lot of options because it's a popular size. I'm still running the stock junk but plan to stick with this size when they finally wear down enough. I ran oversize tires on my last rig for years and you get used to the speedo being off pretty quick. Just use a GPS or app on your phone to compare reality vs indicated speed and it'll be an automatic calculation in short order.One thing to consider is your spare. One if you can fit a larger size replacement, or two if you don't I'd be careful about going too far with the spare on the rear if you have limited slip.

Did you notice any change in MPG by running a larger tire?

There is a quarter inch of height different between the two and your speedometer will be off by about 1 mph at 65. Your stock tire rotates 618 times in a mile, the new size would rotate 608 times.Any difference in fuel economy would be more influenced by tire weight. I think the difference would be very minimal. For the price savings and wider selection of tires, I would make the change.

My guess is you'll notice no change. The two are only 1/2" different. That equates to 1/4" on the ground. That's no different than driving a brand new tire and one that's worn out.

only about 0.55" larger in diameter. probably will not notice a change

LT265 vs LT275 | Good Sam Community

jstaffon
Explorer
Dec 11, 2016
Thanks all for your input! I love this forum!
transferred
Explorer
Dec 11, 2016
Biggest advantage to going bigger could be increased weight capacity depending on the tire.

My 285/70R18 Nitto Terra Grapplers are rated at 3750 lbs each giving me 15k lbs of tire capacity on my SRW 3500.
Greene728
Explorer
Dec 11, 2016
I myself doubt you'll see any changes at all. Especially with the Dmax.
ChooChooMan74
Explorer
Dec 11, 2016
I did something similar to you in my EcoDiesel, except I went slightly smaller (And smaller wheel diameter). Biggest factor, IMHO, would be going to a more agressive tread pattern.
JustLabs
Explorer
Dec 11, 2016
Greene728 wrote:
I myself doubt you'll see any changes at all. Especially with the Dmax.

He won't notice any difference. I replaced the junk OEM 265/70/18 Goodyears on my 2500HD with 275/70/18s shortly after I bought it.

At the time, there were exactly two different tires in the OEM 265 size to choose from. I went 275s to open up the tire choices.
2naEagle
Explorer
Dec 12, 2016
https://tiresize.com/comparison/

Tire Size Comparison
bucky
Explorer II
Dec 12, 2016
This change would have minimal effect, but remember to have the truck reflashed if you have a bigger change in size.
A bigger change will have an impact on shifting and fueling. Most tuners can correct tire size even on a stock tune.
Be aware that at least for GM and Ram the dealer can only reflash to a factory size offered on your truck, forcing you to a tuner.
transferred
Explorer
Dec 12, 2016
bucky wrote:
This change would have minimal effect, but remember to have the truck reflashed if you have a bigger change in size.
A bigger change will have an impact on shifting and fueling. Most tuners can correct tire size even on a stock tune.
Be aware that at least for GM and Ram the dealer can only reflash to a factory size offered on your truck, forcing you to a tuner.

No, he does NOT need a reflash after increasing the diameter of his tires by a half inch.
A two, three or four inch jump, it may be a good idea.
The_real_wild1
Explorer
Dec 13, 2016
My stock summer tires are 265. The winter tires I bought are 275. There is the slightest difference but I only noticed the first day. It is more of a noise and vibration then anything. Go ahead and put them on.
Latviaman
Explorer
Dec 13, 2016
I have 2012 3500 SRW and run the original 265 70 R18 most of the year. But I also have 275 70 R18 winter tires. My 275's rub the plastic wheel well behind the front tires if I turn sharply. My winter tires are studded Coopers. Hope this helps.