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Go from 265s to 285s or 305s on my 1 ton? Or stick with the 265s?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 84_Chevy_K10, Apr 14, 2002.

  1. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Okay. Looks like the left rear tire on my '87 1 ton has a belt seperation (I found a bubble in the tire by accident). It also has C load rating tires which aren't sufficient for the new 5th wheel we just bought which weighs over 8,000 lbs. empty.

    Right now it has what I'm pretty sure were the stock size tires for it, 265/75R16, which are 31.6" tall according to the calculator (and if anything, they're shorter in real life).

    I'm going to step up to a set of rear tires that are D or E load rated. I am thinking of going taller because this thing has no overdrive and it's really rough to turn that many RPM unloaded. The only thing is, I want to be sure that I'll be able to pull my new 5er just as easy as before. It'll drop from 3,200 RPM @ 65 to about 3,000 if I have 4.56s, and 3,000 to 2,800 if I have 4.10s (I'll know by the end of the day, I'm pulling the cover).

    So, if you were me, would you step up to a set of 33s in the rear, or stick with the 31.6" tall 265s? They'll be E load rated 80 PSI tires anyway, so, would you go a little taller?
     
  2. Hossbaby50

    Hossbaby50 3/4 ton status

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    The 265 BFG's my dad has on his 92 F350 are only 31". Not the 31.6" claimed. This height was measured brand new. Personally, if your motor has the grunt to be able to pull the 5th with the few hundred RPM difference I would go with the 33's. Save yourself some gas.
     
  3. Zeus33rd

    Zeus33rd Smarter than you GMOTM Winner

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    And ya dont have to pull the cover to find out what ratios ya got. Jack it up and turn the drive shaft, count how many times the tire does around. If it goes around 4 1/2 times, you have 4.56's. 4 times and it's 4.10's. Or maybe you turn the tire and count the revolutions of the driveshaft..Hmm....I cant remember...lol...It's one of the 2 though.
     
  4. Hossbaby50

    Hossbaby50 3/4 ton status

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    Ya, you can rotate the tire and count the number of revolutions of the driveshaft, but if he is getting ready to haul a 5th wheel trailer all over hell and gone then dropping the cover and changing the gear oil isn't a bad idea. Help keep the diff happy, and you on the road.
     
  5. 84_Chevy_K10

    84_Chevy_K10 Banned

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    It leaks anyway, and I'm going out to pull the cover right now, straighten it, put a new gasket on it, and fill it up with some fresh gear lube.

    I have never pulled this 5er with this truck so I don't know how it's going to pull, however, before I hitch up 9,000 lbs of trailer and 2,000 lbs. of pin weight I want to get a new set of tires on the back of this thing, specifically a left rear without a huge bubble in the sidewall. I know GM says this truck can pull 10,000 lbs. of trailer, but I just wanted opinions on whether or not it'd pull okay loosing about 200 RPM at a cruise speed.

    I'll go pull the cover right now so I can figure out what ratio it has and it'll be easier to get opinions.
     
  6. Hossbaby50

    Hossbaby50 3/4 ton status

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    What motor is in the truck? If it has good power you might get way with the taller tire, but if you think it might struggle then the smaller tire might be the better choice.

    My dads '92 F350 pulled a 5000+/- trailer over flat ground with 4.10's and 265's like it wasn't even there. But the truck also has a fuel injected 460 with only 90K on the motor. This truck is a dual cab single rear wheel, and it will spin the tires off the line. It has pretty good power.
     
  7. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Back from the garage, that monster 14 FF is draining. I sprayed it out with some brake cleaner too and found the all wonderful 41 10, yep, 4.10 gears. I was kinda hoping for 4.56s since this trailer is pretty heavy.

    Anyway, it's got a 350 with TBI that runs pretty good. It's got 140,000 miles on it and nobody ever towed with it. It doesn't leak and it only burns oil on startup (valve seals) and even then not even enough to smoke (but you can smell it).

    I'm thinking I'm just going to put a set of 265/75R16 Ds or Es on it now that it has 4.10s. What do you guys think? Is 2,800 enough RPM to pull my trailer comfortably down the highway?

    I have never pulled anything this heavy so I'm not exactly sure.
     
  8. AJMBLAZER

    AJMBLAZER Better to be lucky than good. Premium Member

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    You could also consider 255/85R16's. Slightly taller than 33" (just enough to notice a difference between them and 285's) and about 10.1" wide. Usually a high load rating, D or E, and also rather cheap. Even the BFG MT's go for around $140 a tire here. Cooper makes a nice 255 with E load rating in their newer S/T "super all terrain" tire./forums/images/icons/smile.gif
     
  9. Hossbaby50

    Hossbaby50 3/4 ton status

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    Ya, I agree with you. I would put on the 265's with a 350 TBI. If you had a 454 TBI I might try the next tire size but wtih a 350 I have to say 265's. Thats what is on my dads truck, and it pulls well out of the hole with 4.10's. I would run the 265's to help get the 5th wheel rolling from a stop. Also you might want to think about getting a free flowing exhaust and intake system to help with power for the 350. My Dad did a catback exhaust on his F350 after putting in a highflow catalytic converter, and it helped it run a little easier and make some more power. He also put in a K&N filter to help get some more air to the motor, and an MSD ignition coil to help get some more energy for spark. They all helped.

    This summer I plan on doing something to the intake pipe because Furd put the intake pipe in a horrible spot that has no airflow. They also put in a baffle in the tube from the airbox to the throttle body that I am going to modify if possible to help with airflow.
     
  10. 84_Chevy_K10

    84_Chevy_K10 Banned

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    It's 2wd so it'll be All Terrains, no mudders on a 2wd. Think they'll be okay?

    I'm open to suggestions. If it'll pull this trailer down the road 65-70 mph no problems with the larger tires, I'll put larger tires on it.

    Although I do have some 35x12.50R15 All terrains, I could just get some cheap 8 lug 15x8 wagon wheels and throw those on for highway cruising, but I think 35s are a little big when it's got 31s on the front.

    The 255/85R16s sound great, 33.1" tall, 10" section. I think I will go with those if the general census is that I can have a little more tire out back. I like the fact that they're narrower. I don't need wide tires on a 2wd.
     
  11. AJMBLAZER

    AJMBLAZER Better to be lucky than good. Premium Member

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    Hmmmm........since it is 2wd, I'd say stick with the 265's. Some of the E rated tires are actually a bit taller than their C and D rated counterparts, even though the size is officially the same.

    Since it's 2wd a 33" would be kinda a waste. You'd be wasting towing power just turning the tires./forums/images/icons/tongue.gif
     
  12. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Yeah but I've got to cruise empty too, and this thing has LOW gears and no overdrive...that's the only reason I was considering taller tires.

    I think I'm going to stick with the 265s.
     
  13. 84_Chevy_K10

    84_Chevy_K10 Banned

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    It'll definitely get a free flowing exhaust. No cats, true duals, and probably Dynomax or some other fully welded muffler. I want it to be quiet though...if it had OD, or turned less RPM atr cruise, it'd be straight piped like my K10.
     
  14. pcorssmit

    pcorssmit 1/2 ton status

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    Depending on how much towing vs. empty running you plan to do, the 255s may not be a bad choice. The most I've ever towed with a TBI 350 was a CJ on a trailer, maybe 5000 lbs total, behind a 1500 Sub w/3.73s and 31s, it did fine.

    I run the 255/85s on my DD and have been happy with the size, they work good in the snow too. FWIW I run the Remmington Wide Brute RVs, same tire as the Dunlop Radial Rover RVs, but cheaper. Most 255s are D rated, but the actual weight capacity on mine was the same as the 245/75 E's I replaced.

    Pete
     
  15. 84_Chevy_K10

    84_Chevy_K10 Banned

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    It'll be about 50/50 towing/not towing.

    Do you guys think my truck came with 265/75s or 235/85s from the factory?
     
  16. pcorssmit

    pcorssmit 1/2 ton status

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    If I had to wager a guess, I'd say 235/85s.

    Another thing to consider is how fast you plan to drive it, not sure what the speed limits are out there. Here in CO its 75 on the open interstate, so a taller tire is nice on the highway. If you don't run on the interstate much, or don't mind going a little slower when pulling the trailer, this may affect your decision too.

    Another thing you could try is borrowing a pair of tires/wheels from a friend and seeing how it tows, also see if you have room on the front for bigger tires (so you can still rotate them).

    Pete
     
  17. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Speed limit here is 55 MPH while pulling a trailer but I'll probably end up cruising around 65 MPH or so.
     

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