Tire size and increased off road capability

[Frontline]

Looking for a real answer please. Aside from looks what if any advantages are there for going from a 30 inch tire (265/65) to a 31.5 (265/70) or 31 inch (255/70). Trying to decide what size winter tires to buy. If I change sizes then will purchase the electronics to change the speedometer as well. So if I change to a larger size also need to have same size useful summer tires as well.

By the by, I have a 2004 v8 with OME 885 in front and 895e in the rear for a level 2.5 inch lift. This is my ski truck and play truck for summer. 1000 miles a week will be on pavement and snow in winter and pavement and dirt roads in summer. Maybe 10 days a year truly off road on trails.


Insight would be greatly appreciated.

Thanks in advance.

 

[BlackWorksInc]

You'd gain .5~.75" of ground clearance by adding one of the tires you proposed, that's the obvious benefit. The more subtle benefits come from the type of tire you plan on going with.

So how dedicated a winter tire are we talking? Studded? The reason I ask is because there's a good selection of AT's that can cover a good amount of the spectrum (particularly if this is a play truck). My Nitto TerraGrapplers tend to do well in snow and mud for AT tires, though in the thick stuff they get loaded up after a bit; others have had good results with BFGs and such. MT's are decent in snow, though on Toyo's website they rate their new RT class of tire better in snow than their MT (the RT being a cross between an AT and MT, I'm actually considering these when I go to a 35" set-up). Also are you looking at specifically P-Rated tires or LT-Rated as well?

Also why such a small difference in diameter? It sounds like you're running a good sized lift, why not shoot for a 32" or 33" tire, some trimming might be needed up front for the 33" if you're not running a full metal bumper for clearance. Additionally I'm not saying not to get a Speedohealer to correct the accuracy if you get new tires, but even at 31.5" you're looking at a 3.4% difference in speed; that's pretty minor since at 67mph you're speedo will read about 65mph. I installed a speedohealer on my 4th gen because my 33" were a 7% difference from stock which translated to going 70 when my speedo read 65mph.

Not trying to steer you away from your decision, I'm just trying to better understand what you're looking for.

 

[kevinpt]

im running 255/70/18(255/75/17) 32's and at 70 im only doing 74 so i see no need to change the speedo. as long as i dont go over "70" i will not get pulled over for speeding. i also will not fix the speedo because even with the larger tires the truck is spinning at the same speed to even if you are going farther then the truck says you are putting the same wear on the truck as if you did not have larger tires

 

[Frontline]

I am either planning on going with a blizzak or a stud able snow. Need ice performance. Size is still in the air. It is completely open. It is more about what fits. The big question I have is why is bigger better? Aside from looks what does the additional size offer? I am looking a both P and Lt tires mostly based on which tire is available.

 

[Frontline]

im running 255/70/18(255/75/17) 32's and at 70 im only doing 74 so i see no need to change the speedo. as long as i dont go over "70" i will not get pulled over for speeding. i also will not fix the speedo because even with the larger tires the truck is spinning at the same speed to even if you are going farther then the truck says you are putting the same wear on the truck as if you did not have larger tires

Do the 255/75 rub a lot? Have you noticed big decrease in fuel economy?

 

[KidVermicious]

Looking for a real answer please. Aside from looks what if any advantages are there for going from a 30 inch tire (265/65) to a 31.5 (265/70) or 31 inch (255/70). Trying to decide what size winter tires to buy. If I change sizes then will purchase the electronics to change the speedometer as well. So if I change to a larger size also need to have same size useful summer tires as well.

By the by, I have a 2004 v8 with OME 885 in front and 895e in the rear for a level 2.5 inch lift. This is my ski truck and play truck for summer. 1000 miles a week will be on pavement and snow in winter and pavement and dirt roads in summer. Maybe 10 days a year truly off road on trails.


Insight would be greatly appreciated.

Thanks in advance.

First off, going from a 30 to a 31.5 or whatever, you won't need to adjust your speedo unless you really want to. Here's a calculator: https://tiresize.com/speedometer-calibration/ - play around with that and you'll see that in the tire size range you're talking about, speedo correction is hardly worth it.

Second, offroad capability, you'll gain a bit. An extra half inch or inch under the axles doesn't seem like much, but every fraction of an inch you gain in clearance opens up new lines through an obstacle that weren't available before. Folks also forget that a larger tire grants a higher angle of attack when rolling over something, which makes getting a tire up a rock or ledge much easier, and again, fractions of an inch matter.

You probably won't notice that difference though, not unless you are really tuned into what your truck is currently capable of. If you're looking for a noticeable increase in your offroad capability with a bump in tire size, I'd consider a 265/70 the smallest you should be considering, and a 285/70 would be better.

 

[kevinpt]

Do the 255/75 rub a lot? Have you noticed big decrease in fuel economy?

i was running ths size stock with only the fender liner moved up some. not im lifted about 2 inches and have spidertrax spacers, had to trim the bumper from the wheel spacers but i dont rub at all. i went with a 255 for light weight and went with a 32 for ground clearance. mpgs are affected but not by much. i think i went down .5mpg when i was stock. now with a lift i cant say because of other factors like roof rack and such

 

[kevinpt]

the big thing about going with a larger tire is having the axles higher off the ground. you could have a 6" lift but it will not help get you rear axle over a large rock if you dont have a larger tire to lift the tires higher off the ground

 

[Frontline]

Thanks for all the insight! I truly appreciate it.

 

[Billynath1988]

Do the 255/75 rub a lot? Have you noticed big decrease in fuel economy?

I run 255/75/17's in BFG mud terrains, they were jeep rubicon take off's. (can be found very jeep for brand new tires)
I have the daystar 2.5" spacers installed. I had to remove the front mud flaps which takes all of 2 seconds. Otherwise even during off roading it does not rub at all. MPG only took a small almost unnoticeable hit if any at all.
Speedo is also only off slightly, but as stated earlier, the faster you go the higher the speedo is off. I think ride quality improves with taller sidewalls but cornering performance takes a small hit depending on the tires you go with, not that it matters since you drive a truck not a sports car. Its a great size upgrade all around for a mostly stock vehicle and there really is no downside.