How does 275/65/18 effect MPH and MPG?

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SWUtah

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My LX470 has 275/65/18 versus the OEM 275/60/18, so how does that effect the MPH and MPG? I assume that when I am doing what my speedo indicates is 60 MPH that I am really doing over that same with MPG. I know others have this larger tire size. can someone let me know the answer?
 
I dropped 1.5-2 mpg when I changed out my 60's for 65's. But it's not just size difference that lost my milage (and power). My oem 275/60/18 were bald passenger tires. My new 275/65/18 all terrains are E rated truck tires. So while being an inch taller, I'm pretty sure the performance difference came mostly from the ~12 lb per tire weight difference and the more aggressive tread pattern.

Enjoy the tire threads...
 
Your speedo won't be off by much. Actually, with stock tires, the speedo is under the actual MPH, so the upsize should put it almost right on.

I also agree with twicewithhair.
 
I am very interested in this topic as my 2000 LC has 2006 18" wheels with the 275/60 tires. I noticed it riding a little rough and noticed that my brother (previous owner) had replaced the front shocks with Bilsteins. I changed them for stock shocks from Toyota and there was a BIG difference....rode much better but it still doesn't handle bumps as well as I thought it would. I am currently running the Michelin Latitude HP Tour tires and feel that they are better suited for a cross over vehicle and not a LC. Does anyone know if the 2000 LC has different spring/torsion bar settings than the 2006 model? I am not really happy with the 18" wheels and have been considering purchasing a set of stock 16" like it was built with....any thoughts? My other thought was to get some Michelin LTX M&S2 tires in the 275/65 -18 size as I know they have to be better than the Latitude HP Tours but was concerned about the mileage/power/speedo changes.
 
jburris11 said:
I am very interested in this topic as my 2000 LC has 2006 18" wheels with the 275/60 tires. I noticed it riding a little rough and noticed that my brother (previous owner) had replaced the front shocks with Bilsteins. I changed them for stock shocks from Toyota and there was a BIG difference....rode much better but it still doesn't handle bumps as well as I thought it would. I am currently running the Michelin Latitude HP Tour tires and feel that they are better suited for a cross over vehicle and not a LC. Does anyone know if the 2000 LC has different spring/torsion bar settings than the 2006 model? I am not really happy with the 18" wheels and have been considering purchasing a set of stock 16" like it was built with....any thoughts? My other thought was to get some Michelin LTX M&S2 tires in the 275/65 -18 size as I know they have to be better than the Latitude HP Tours but was concerned about the mileage/power/speedo changes.
Click to expand...

Don't bother won't change a thing.
 
I think it can make a big difference going from a P to LT tire and if you go from load D to E rating. I moved up to the LT275/65-18 (Michelin LTX A/T2, Load E) from the OEM tires (Bridgestone Dueler HT P275/60/18 Load D). These Michelins are 53.1 lb per manu website and about 41 ish lb for the Dueler HT). I also inflate current set of tires higher than what was on the door jam based on a load table (like 39/42) now. I believe the OEM tires were running like 29/32.
 
In addition to speed change the weight per tire can significantly hit mileage...my nittos are 25 pds heavier per corner. Get 12mpg around town mixed driving
 
I replaced my tires not so long ago with Michelins LTX A-T2 275/65 18.

The speedo is spot on now and I lost about 1 mpg. I average about 16 mpg now. I'm an easy rider..
 
I just threw some Michelin LTX A/T 275/65/18s on my 02 and it drives like a new car. Not sure about mileage yet but will post soon. I just removed some Pirelli Scorpion ATRs in a 285/75/16
 
dogdaysindurham said:
I think it can make a big difference going from a P to LT tire and if you go from load D to E rating. I moved up to the LT275/65-18 (Michelin LTX A/T2, Load E) from the OEM tires (Bridgestone Dueler HT P275/60/18 Load D). These Michelins are 53.1 lb per manu website and about 41 ish lb for the Dueler HT). I also inflate current set of tires higher than what was on the door jam based on a load table (like 39/42) now. I believe the OEM tires were running like 29/32.
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M/S2's are not D/E rated or as heavy as the truck D/E tires. Apples/oranges
My 275/65/18 MS'2s only weigh 1lb more then the OEM 275/60/16's.
 
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SWUtah said:
I just looked again mine are 265/70/18 Michelin LTX M/S2's so about 5.2% bigger then stock. So at 60 mph I am doing almost 63 mph. Should also change my MPG by 5.2% so if I think I am getting 15 mpg I am really getting about 16.5 MPG.
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Highly doubtful. Check your gps. I'd wager you're getting very close to indicated speed.
 
Sorry for pulling up an old thread...I'm looking at putting P275/65 18 LTX AT2s on a stock 06 LX. We tow a 4400lb pop up camper a lot on the freeway and in the Georgia mountains. Has anyone towed with a 1" taller tire and noticed difference over stock? I love how effortless towing is now and I would hate to change that. Also, wouldn't I get slightly better hwy mpg since the tire is rotating less?
ImageUploadedByIH8MUD Forum1406149852.316764.webp
 
Forgot to ask about any noticeable differences in braking with a slightly larger tire? Thanks.
 
I tow a utility trailer, snowmobile trailer, or small boat trailer with 275/65-18 LTX AT/2 standard load tires (not the heavier E rated). Works fine, no issues. And yes, your calculated mpg will be lower than actual by the percentage difference in tire circumference when going to a larger tire (and your speedometer will read too high by the same percentage).
 
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