Another Tire Thread-LT285/70R18 Only!

I’m currently running LT275/70R18 Goodyear Ultraterrains (55lbs) on stock TRD Pro wheels (18x8). I have slight lift of about 2.5” in from on TRD Pro Fox with Couchbulder shins and about a 2” lift from custom Alcan springs in rear. I am currently getting at best around 15.1 combined MPG. I don’t think I noticed any power/acceleration/shifting loss, but I switched from OEM 275/65R18 (maybe 47lbs?)the day after buying my Tundra. My Speedo also seems exactly correct up to 90mph according to GPS.

Every time I look at my truck from anydistance, those 275’s look a little small proportionally to the size/lift of the truck. I am looking at jumping up to a LT285/70R18 Nitto Exo Grappler(64.27lbs) on the same Pro Wheels. Question is, have those running the 285’snoticed MPG loss, Power loss, Shifting issues, Speedo difference?

I don’t want to get into re-gearing or having to use the hypertext to reset Speedo. 1-2 mph difference is livable. I know there are a lot of threads for Tires, I’ve read just about everyone. Most areabout 295’s or larger, or the 275’s, and mostly only ask about rubbing (Not my concern). Appreciate input from those on2.5 Gen Tundras running LT285/70R18’s. Pretty much only tires in that size are Nitro Ridge or Exo Grappler and a few otherbrand MT’s.

 

I haven't really noticed. I don't pay too much attention to it since it's not the most fuel economic vehicle on the road.

 

Speedo difference is about 8%. Yes, I have noticed a change I'm acceleration, both ways. It's a heavier, larger diameter tire than the OE tire. I am getting 15-15.5 mpg, calculated, combined in the 3k miles I've had them on. But they're awesome, so who cares.

 

Thanks! Yeah, definitely didn’t buy a Tundra for fuel economy, just trying to find the balance. Your truck with those tires looks good!

 

Hell, your MPG is about the same. What would you say your Speedo diff is at about 75? Reading 1-2 MPH lower than actual?

 

Yeah those are the RG 285/70's. The lift is a right at 4 front and 2 rear.

 

I’m looking at the Cooper Rugged Treks LT275/70R18, run about the biggest I’ve seen for that size. According to Cooper; 33.66”, 11.1”, (measured on a 8” wide wheel) weighing 59lbs with 18.5/16” tread.

OR

Nitto Exo’s in LT285/70R18. According to Nitto; 33.98”, 11.50”, (measured on a 8.5” wide wheel) 64.27lbs with 18.4/16” tread.

 

On my second set of 285/75. First was duratrac. The second set (2k miles so far) is the Geolandar X-AT.

Mileage is about the same between the two - 14.5ish. The X-AT are a muuuuch more comfortable ride, IMO.

There’s certainly a lag from what I remember stock was (it was a bit ago), but nothing that I can’t live without. I’ve also added a lot of other weight since then too, so she’s heavier than she was. Camper shell, steel bumpers, RCIs, etc. It’ll still get up and go when needed though.

Speedo difference is the same as @DZ_ - 8%. 65 on the speedo is actually 70…ish. I’ve never corrected it.

Here’s the other details:
6112 fronts at 2.5”
5100 rear with TT shackle at 1”
Expedition One front bumper
Stock UCA
Stock 2017 TRD wheels

 

It's a proportional difference, because the diameter of the tire is larger. It's approximately 8% as calculated on the tire size calculator websites and verified with GPS. If your speedo says you are going X mph, you are actually going X*1.08 mph. Same for the odometer.

 

Fix your title.

285/70s are ~6% larger diameter vs stock. But 285/75s are what you really want... or better yet, 37s.

 

Thanks rruf, I didn’t even notice I screwed up the title until you pointed it out. I got it fixed. I’ve been looking at the tire comparison calculators. 6% doesn’t seem like much. Wanted to hear some real world experience in how it affected Tundras.

 

I went from p275 65 18 to 275 70 18 E and 285 70 18 E. Lost about the same pep and MPG in each step. Now at 12-13 in town - 15ish on the highway.

Speedo is only 1-2 off for city speeds. 3ish highway speed.

 

The above link will allow you to compare different tire size, speedo differences, proper PSI to achieve the same load rating on different tire sizes, and even wheel offset examples.....

 

I can tell you my experience with bigger tires. There was a little less grunt off the line, but I was used to it after a few minutes. Nice thing about a 400hp V8 is that it has plenty of power... you can press on the pedal a little harder if you want more. I don't worry about the MPH and ODO reading low, just take it into account.I actually get better MPG around town than I did with the stock Bridgestones, but that won't be the usual result.

Speaking of the pedal... one thing I did that helped a lot was getting a throttle controller (HikeIt X5). I really hated the way the ECU mapped the throttle. Disabling traction control (which slows you way down and even stops you if the wheels spin) helps a lot too, if you are ever in a situation where you really want the truck to move. There is also the Tow/Haul button which makes the throttle and shift points more responsive.

 

Awesome info, thanks!