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Looking for suggestions on 275/70/18 Size Tires??

Discussion in 'Wheels & Tires' started by bigbuck493, Feb 9, 2014.

  1. bigbuck493

    bigbuck493 Member

    hey yall im runnin 3.08's 6 speed tranny and this summer im gettin a afe prodry s performance panel filter and next summer will be getting a Airaid modular intake tube basically making my stock airbox a CAI and ill be doing a flowmaster super 10 on. i was just wondering if going from a p metric 265/65r18 highway+snow tire to an LT275/70r18 goodyear duratrac at tire. plus a 2.5 inch lift, am i gonna hurt my drivetrain going up so much in weight and stance and everything on the tires + the lift? im lookin for all suggestions to keep the difference minimal guys!
  2. 99'HEARTBEAT

    99'HEARTBEAT Epic Member Staff Member 5+ Years ROTM Winner 1000 Posts Platinum Contributor


    Here are Specs on Both Tire Sizes you've Mentioned,


    [TABLE="class: cms_table_withlines, align: center"]
    [TR]
    [TD="align: center"]Tires:[/TD]
    [TH]Tire 1[/TH]
    [TH]Tire 2[/TH]
    [/TR]
    [TR]
    [TH]Tire Size[/TH]
    [TD="align: center"]265/65-18[/TD]
    [TD="align: center"]275/70-18[/TD]
    [/TR]
    [TR]
    [TH]Section Width[/TH]
    [TD="align: center"]265 mm (10.4'')[/TD]
    [TD="align: center"]275 mm (10.8'')[/TD]
    [/TR]
    [TR]
    [TH]Sidewall[/TH]
    [TD="align: center"]172 mm (6.8'')[/TD]
    [TD="align: center"]193 mm (7.6'')[/TD]
    [/TR]
    [TR]
    [TH]Tire Diameter
    [/TH]
    [TD="align: center"]801 mm (31.5'')
    [/TD]
    [TD="align: center"]843 mm (33.2'')
    42 mm (5.2%) Taller.
    [/TD]
    [/TR]
    [TR]
    [TH]Rim Sizes[/TH]
    [TD="align: center"]18x7.5 to 18x10[/TD]
    [TD="align: center"]18x7.5 to 18x10.5[/TD]
    [/TR]
    [TR]
    [TH]Circumference[/TH]
    [TD="align: center"]2515 mm (99'')[/TD]
    [TD="align: center"]2647 mm (104.2'')[/TD]
    [/TR]
    [TR]
    [TH]Revs per mile[/TH]
    [TD="align: center"]639.9[/TD]
    [TD="align: center"]608[/TD]
    [/TR]
    [TR]
    [TH]Typical Weight[/TH]
    [TD="align: center"]~ 45 lbs / 20 kg[/TD]
    [TD="align: center"]~ 51 lbs / 23 kg[/TD]
    [/TR]
    [TR]
    [TD="align: center"][/TD]
    [/TR]
    [/TABLE]


    With the 275/70/18's when Your Speedometer Reads 60 MPH......Your Actual Speed will be 63.1 MPH or 5.2% Faster.

    ....Also with this change in Tire Size, the Speedometer Will Need to be Re-Calibrated, As the Trucks Computer Calculates your Speed Based on the Diameter of the Stock Tires. By Installing Taller Tires, the Trucks Computer doesn’t know how Fast your going. As a Result, the Automatic Transmission may Not Shift Correctly and the Speedometer Readings will Not be Accurate (as required by law).

    ....With the 3.08 Gears and the Tires 275/70/18's having a Overall Diameter of 33.2in".....your Performance will drop off....you can use this Gear Ratio and Tire Size Chart (Below) as it shows what Tire Size, to Go with your 3.08 Gears....regarding Performance and Fuel Mileage.

    [​IMG]
    Last edited: Feb 10, 2014
  3. bigbuck493

    bigbuck493 Member

    wait... it doesnt even show anything for 3.08 and 33's? lol and im just wondering performance wise and trimming wise
  4. 99'HEARTBEAT

    99'HEARTBEAT Epic Member Staff Member 5+ Years ROTM Winner 1000 Posts Platinum Contributor

    Correct....this 3.08 and 33in" Tall Tires Setup is not on the Chart, your Performance would be poor with this Gear-n-Tire Setup, as you see from the Chart, you'd want to be in the Green Section to receive Good Performance and Fuel Mileage, with the 33in"Tall Tires you've mentioned....you would be looking for Gears in the Range of 3.73...3.91 or 4.10 Gears, to maintain Good Performance.
    Last edited: Feb 11, 2014
  5. bigbuck493

    bigbuck493 Member

    but my 3.08 came stock with p265/65r18 which it also doesnt show that tire for the 3.08's so i guess im confused
    i mean i wish it had 3.42 but i bought it like that and i aint about to void warranty by installing new gears
  6. bigbuck493

    bigbuck493 Member

    im just confused because this is rhe stock tire they put on these trucks?
  7. Chevycoastie

    Chevycoastie Member

    Bigbuck493,

    I am in trhe same boat when it comes to tires. I have a 5.3, 6 speed auto, 2wd, 3.08. I am running 275/55R20. This is all stock from dealer. I've been looking at a leveling kit since I am only 2wd and also looking at a step up in tire size. For our trucks to get the best perfomance we have to stay with the same tire size. This came from good friends that work at a dealer. The only way to step up tire size with your lift is to change your rear end gears. Some models of our trucks came with either 3.42 or 3.73. My boss has the same year and model I do but his is 4wd. His gear set is different than my set and he can step up tire size unlike me. I hope this has helped you out.

    Gene
  8. bigbuck493

    bigbuck493 Member

    ive read that going from 265/65 18 to 275 70 18 should be okay im just trying to see if anyone else has some advice or anything because i dont wanna mess up the rear end of the truck
  9. Chevycoastie

    Chevycoastie Member

    Bigbuck493,

    I spoke to a buddy of mine at my local chevy dealer and he recommends 285/65/18. They put that size tire and our make and model all day long. He told me that your drive train will be ok. All that you are doing is going up a size. The only difference you might see is your MPG and your speed will be different.
  10. WorthFlorida

    WorthFlorida Member 1 Year 100 Posts

    If you want a taller tire then you move up but if you want a wider tire, 265 vs 285 you need to change the aspect ration to keep the tire diameter about the same. To go to 285 it should be 285/55/18 (if they make one). My Silverado came with the "Florida" package with Goodyear Eagle LS-2, 275/55/20 and the truck has a 3.42 posilock rear. I get 19 plus on the highway (70MPG) and pretty good acceleration yet the above chart reads it in the yellow. The tires are just under 32" and impressively wide.

    At Tirerack they have a nice chart. Click on this link and then select the SPECS tab at the bottom. It has a full list of all tire sizes and their respective numbers that will fit your truck.

    http://www.tirerack.com/tires/tires...Model=Silverado 1500 4wd&autoModClar=Crew Cab

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