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Gears (4:56 or 4:88)? Rims (16.5 or not)?

Discussion in 'The Garage' started by Kingston, Jul 17, 2005.

  1. Kingston

    Kingston Registered Member

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    Location:
    Alberta, Canada
    I just installed a 3/4 ton running gear in my blazer (14 bolt FF rear & 10 bolt front) I have a 454 ,TH350 and a NP208 and new set of 38X15.5x16.5 Radial TSL's, which actually measure 37". I was wondering what gears to go with, 4:56 or 4:88? My concern is at highway speeds like 60mph & 65mph my rpm will be way to high with no overdrive. Im trying to stay in the powerband at all speeds, which is 2200-2600 rpm I believe for a big block such as mine. I am going to be doing a lot of highway driving to get to places to go 4X4. I'am also worried by going to 4:88 the ring and pinion gets to small on the 10bolt and there is more chance of breakage. As for the rim I just realized that there is no safety bead on 16.5 rims, after I just purchased them of course, from kal-tire. Im thinking about returning them because I have read so much about how they come off the rim so much when aired down, which I plan on doing alot. However I wanted big TSL's and radials since I required to do alot of highway driving. I am limiting the tire height to max 38" because of the weak 10bolt. I thought 16.5 would be a good choice since 15" rims have problems fitting on 3/4 ton running gear and since there is no 16'' rims for the type & size of TSL'S I wanted .Does anyone have some much needed advice? Thanks!
     
  2. 454k30

    454k30 1/2 ton status GMOTM Winner

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    A question like this opens up a lot of opinions. So I will start by saying Imho. I do not like 16.5 inch rims but if air pressure are kept at 30psi+ levels I have never seen one come off the rim. I think that 38's are to big for 10 bolts unless you dump a bunch of money into the axle and then you could've gotten 1 ton gear for about the same or less of the green stuff. If you can get your money back then great, get the same size tire but on 16's! Gear choice is also a BIG opinion popper but I have 37's, run 4.88 gears, and often wish I had gone with 5.13's. Big tires are hard to turn, and overdrive or not the highway efficiency will either stay about the same or it will fall. I think that unless you do some really low pressure wheeling that your 16.5's will do you fine. and get some steeper gears so you dont kill your tranny, at least the 4.56's.
     

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