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Do i REALLY need to regear???

Discussion in 'Lifted & Offroad Suspension' started by harts2009, Feb 25, 2013.

  1. harts2009

    harts2009 New Member

    I have a 2012 crew cab z71 5" rcx lift factory 20's and currently running 295/60/20 trail grapplers with factory 3.42 gears, hypertech max energy on 87 tune, and magnaflow exhaust. I do not off road and very rarely will i tow anything. I have noticed with these tires my 6th gear is pretty much useless, so i have been just putting the truck in M5 and driving. I am avg. about 16 mpg right now. Is it really worth the $1500.00 to regear to 4.56 gears? Would my mpg really go up much? I have also been debating on going down in tire to help instead of gears and maybe this would allow me to use 6th gear with my 3.42s, looking at a 275/65/20 toyo open country at2 since truck is never off road. Thanks for your help!
  2. tbplus10

    tbplus10 Super Moderator Staff Member Platinum Contributor 1000 Posts

    You hit directly on part of the issue, the money spent regearing will take a long time to recoup at the pump.
    Another part of that is the money you might have to spend for premature wear on parts because of running larger tires, it's a fact larger tires wear-out drive train components faster, just how much seems to vary.
    And finally the performance factor of your truck, with those tires I'm sure throttle response, take-off speed, towing, and in certain terrains just plain driving are affected.
    Only you really know how much this is worth to you, you already know app. the cost of a regear.
  3. Curky

    Curky New Member 1000 Posts

    I would re gear but $1500 you are getting ripped off. I would say $700- $900. I got a quote to re gear and add a locker on mine from the dealer for 1200.
  4. harts2009

    harts2009 New Member

    is anyone else driving in M5 instead of just regular D? Would the truck look weird with a 275/65/20 tire?
  5. 99'HEARTBEAT

    99'HEARTBEAT Moderator Staff Member Platinum Contributor 1000 Posts

    X2......On what tbplus10 has mentioned above.....Here's some information, that hopefully will be able to help you.

    Below are the Specs on the Tire Sizes you've mentioned.


    275/55's
    that came on the Factory 20's...vs the 295/60's

    [TABLE="class: cms_table_cms_table_cms_table_cms_table_cms_table_withlines, align: center"]
    [TR]
    [TH]Tire size[/TH]
    [TD]275/55-20[/TD]
    [TD]295/60-20[/TD]
    [/TR]
    [TR]
    [TH]Section width[/TH]
    [TD]275 mm (10.8'')[/TD]
    [TD]295 mm (11.6'')[/TD]
    [/TR]
    [TR]
    [TH]Sidewall[/TH]
    [TD]151 mm (5.9'')[/TD]
    [TD]177 mm (7'')[/TD]
    [/TR]
    [TR]
    [TH]Tire diameter[/TH]
    [TD]810 mm (31.9'')[/TD]
    [TD]862 mm (33.9'')
    52 mm (6.4%) taller.
    *Seems TOO tall.[/TD]
    [/TR]
    [TR]
    [TH]Rim sizes[/TH]
    [TD]20x8 to 20x10.5[/TD]
    [TD]20x8.5 to 20x11[/TD]
    [/TR]
    [TR]
    [TH]Circumference[/TH]
    [TD]2543 mm (100.1'')[/TD]
    [TD]2707 mm (106.6'')[/TD]
    [/TR]
    [TR]
    [TH]Revs per mile[/TH]
    [TD]632.8[/TD]
    [TD]594.6[/TD]
    [/TR]
    [TR]
    [TH]Speedometer[/TH]
    [TD]Assuming that this is OEM tire and speedometer readings are correct >>>[/TD]
    [TD]When speedometer reads 60mph (96.6km/h) actual speed will be 63.9mph (102.9km/h): 6.5% faster.[/TD]
    [/TR]
    [TR]
    [TD][/TD]
    [TD][/TD]
    [/TR]
    [/TABLE]


    **************************************************

    Here are the Specs on......... 295/60's vs 275/65's

    [TABLE="class: cms_table_cms_table_cms_table_cms_table_cms_table_withlines, align: center"]
    [TR]
    [TD]Tires:[/TD]
    [TH]Tire 1[/TH]
    [TH]Tire 2[/TH]
    [/TR]
    [TR]
    [TH]Tire size[/TH]
    [TD]295/60-20[/TD]
    [TD]275/65-20[/TD]
    [/TR]
    [TR]
    [TH]Section width[/TH]
    [TD]295 mm (11.6'')[/TD]
    [TD]275 mm (10.8'')[/TD]
    [/TR]
    [TR]
    [TH]Sidewall[/TH]
    [TD]177 mm (7'')[/TD]
    [TD]179 mm (7'')[/TD]
    [/TR]
    [TR]
    [TH]Tire diameter[/TH]
    [TD]862 mm (33.9'')
    [/TD]
    [TD]866 mm (34.1'')
    4 mm (0.5%) taller.
    [/TD]
    [/TR]
    [TR]
    [TH]Rim sizes[/TH]
    [TD]20x8.5 to 20x11[/TD]
    [TD]20x7.5 to 20x10.5[/TD]
    [/TR]
    [TR]
    [TH]Circumference[/TH]
    [TD]2707 mm (106.6'')[/TD]
    [TD]2719 mm (107'')[/TD]
    [/TR]
    [TR]
    [TH]Revs per mile[/TH]
    [TD]594.6[/TD]
    [TD]591.8[/TD]
    [/TR]
    [TR]
    [TH]Speedometer[/TH]
    [TD]Assuming that this is OEM tire and speedometer readings are correct >>>[/TD]
    [TD]When speedometer reads 60mph (96.6km/h) actual speed will be 60.3mph (97.1km/h): 0.5% faster.[/TD]
    [/TR]
    [/TABLE]



    **************************************

    Here a Chart, showing what Size Tires, with what Gear Ratio, would work Best.

    [​IMG]
  6. harts2009

    harts2009 New Member

    275/65/20 are a much lighter tire and not near as aggressive, therefor i would figure it would be alot easier to push around and could free up 6th gear and maybe some more mpg. Please let me know if i am wrong?
  7. dsfloyd

    dsfloyd New Member 1000 Posts

    the 275/65/20 is about the same height and almost an inch narrower. They weigh 20lbs less (57 vs 77 lbs), so yes it will help some with the mass of tire the truck needs to push. Your effective gear ratio of the two tires are the same compared to stock (about a 3.2 effective gear ratio so not much taller than the stock 3.42). You may get some mileage back due to the lower weight but you are still less aerodynamic with the lift. So you may also get the use of 6th gear back but I cant say for sure, sorry.

    Also arent the tires gonna cost roughly 1000-1200 for purchase and install as well which is around the cost of gears. In which getting 3.73 would put you back to stock performance (not necessarily mpg due to lift and tires). Kind of a balancing act. with either tire the truck will be a little under powered but may work for you.

    For example I put 4.10 in my truck instead of 4.56 when I lifted due to it, at the time, being a daily driver and I did mostly highway driving. So the 4.10 kept my mileage close to stock but it definately has to work harder in the city to get moving. I will probably regear it again to 4.56 eventually as its not a daily driver any more and especially if I start to do more than the very occasional towing.
  8. harts2009

    harts2009 New Member


    The tire shop i buy from will swap me strait across for a smaller tire
  9. dsfloyd

    dsfloyd New Member 1000 Posts

    ok gotcha. Then cross out the cost comment as the rest still applies. If they are gonna do a straight swap you are mainly going to a tire that is an inch skinnier and 20 lbs lighter. Even has a little less aggressive tread which may help mpg as well. At the cost of free, doesnt hurt to try as I dont think it will change the looks/cosmetics of the truck.
  10. harts2009

    harts2009 New Member

    im just wondering if that tire would be too narrow, but its alot cheaper than regearing and i lose the mud tires which have more resistance compared to an at tire

    - - - Updated - - -

    does ANYONE have a pic of a lifted nnbs with 275/65/20 tires???

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