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Discussion Starter · #1 ·
Hi, I have Rancho RS9000X adjustible shocks on my truck and am getting ready to buy new tires. I'd like to put a taller tire on vs the stock 245/75R16. I'm looking at the Toyo M55 255/85R16 because they will still fit on the stock rim, won't require any cutting of anything. But they are almost 2.5" taller than the stock tires. But they will also drop my engine speed on the highway by about 150 rpm's, which seems to help in the mpg department. It seems if I stay below 1900 rpm's, I get about 3 more mpg on the highway.

I was going to get the new keys I've seen on ebay for the torsion bars to raise the front up and level out the truck. Will the stock size shocks still be OK, or am I looking at replacing them also to make it all work?
 

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just buy some shock extensioners. they arent required but will improve the ride. have u already tryed cranking the stock keys? bc most can get atleast 1.5" out of the stockers, some more.
 

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the stock rancho rsx9000x adjustables you have will work with up to 2"of lift i know i thought i had the same problem till i called rancho before i bought the shocks no extenders need with the 9000's
 

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Discussion Starter · #4 · (Edited)

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They should, but the ones cognito has might work better.
 

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Taller??

Let me get this straight if i go toa taller tire i will improve the mpg's? I have the stock 245s and was thinking about going to 285s or the 265s,if that is the case i'll improve roughly 2-5 mpg?
:beerchug: " The Lord created liquor to prevent the Irish from conquering the world! "

I was going to get the new keys I've seen on ebay for the torsion bars to raise the front up and level out the truck. Will the stock size shocks still be OK, or am I looking at replacing them also to make it all work?[/quote]
:beerchug::beerchug:
 

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on the highway u will most likely gain mpg but city driving will probably drop it alittle.

as for cranking the bars, try and crank with your stock keys, most will get the amount they need with them. you dont have to get longer shocks or extenders but it will improve the ride.
 

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MPGs

Thanks makes sense :cool: Need more power to get them rolling,and when they roll takes a bit longer to rotate. Thanks had to think about it a bit more i guess.;)
 

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Discussion Starter · #9 ·
Let me clarify, I was looking at these tires specifically because they are very similar in weight to the stockers. I looked at the larger tires, 265's and 285's. They are heavier, thereby having more mass to get moving. General consensus on this board from those that have the bigger tires is that while rpm's do go down, your mpg does not get much better because the tires weigh so much more.

Also, the 265's only have about a 1" larger diameter. The 285's are just over 2" larger diameter, but much heavier.

The 255's have a 85 aspect ratio, which is what makes them much taller.
 

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Discussion Starter · #10 ·
OK, I've been looking around here and doing some searches. It seems I may be getting a little more involved here than I had planned.

All I want to do is put a taller tire on the truck and bring the front end up about 2". This will level the truck and give the room I want to make sure I don't have any rubbing issues.

Can I accomplish this with just some shock extenders and new torsion bar keys? Or am I going to need other stuff for the idler/pitman arms?

I saw the Cognito kit here for $120 with keys and lower shock extensions. Do those have to be welded in on the bottom?
 

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70 gsconvt,

When I first got my truck, I changed the 245-75x16 to 255-85x16 on day one. I was running Cooper ATs (I think, they aren't made any longer) and ran this setup for around 60k miles. With the 255s I left the T-bars at the factory height.

I was disappointed in the mileage (30k and tires worn out) on the Coopers so I made the leap to the H2's. The 315-70x17s required cranking the T-bars about 1-3/4", shifting the front bumper out about an inch plus some trimming. I later put 2" blocks on the rear to get the factory rake back. I now have almost 170k miles and still running the factory shocks, w/o any bottoming problems. Now, mine is a 2WD and I don't go off road much, so there may be a problem if you do serious off roading.

Let me know if you have any questions.

MaxRock
 

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Discussion Starter · #12 ·
My truck is a 4x4 and while I'm not an off-roader, it seems every time a "friend" gets stuck in the mud or snow, they're on my cell phone asking for help. I guess I'm just a sucker when it comes to that. I just can't say no to someone in a jam. I've lost count how many people I've pulled out of the mud, snow banks, etc.

I've seen on other threads that there are about 4 or 5 tires made that come in this size. I don't want the BFG Mud Terrain tires, but some of the others with the aggressive all-terrain treads interest me. I wonder which one will give me the best wear and last the longest?

I drive almost exclusively on the road, but don't want to get stuck in the snow, so something that's a little aggresive is OK with me.
 

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i would go with the bfg all terrains, they are probably the best all terrain u can buy, low road noise on the road, offers good offroad traction and good wear and a pretty long life if rotated regularly.
 

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Discussion Starter · #14 ·
OK. I think what I'm going to do is get the front lower shock extensions. I saw them on ebay, $42 delivered. They look like the Cognito's, but I'm not sure. Here's a link to them: http://cgi.ebay.com/ebaymotors/2001...tegoryZ33585QQihZ013QQitemZ230093276105QQrdZ1

Then I'll crank on the torsion bars with the stock keys in place and see if I can gain about 1.5". After all, I'm going with a 3" diameter taller tire, so 1.5" radius.

I must say that I drove my parents 2000 2500 2WD that had brand new Revo's on it and WOW, do those tires provide good traction in the snow. I may end up just getting the 265/75R16 of those. It's not the height I want, but it's supposed to be a great wearing tire and it was quiet on the highway, but had a fairly aggressive tread that really went through the snow well.

Soooooooo, how exactly do I crank these torsion bars to raise the front end? I took a little peak under there, but it's cold out there right now, so no creaper today.
 

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jack up truck via frame so tires/suspension can sag

tighten adjuster screws...about 1/2 way under truck...follow t-bars back. The bolts face downward. Keep track of how many full turns to keep both sides equal and/or measure from center of wheel (not ground...tire squish etc make this an unrepeatable measurement) to fender. 1 full turn (360 degrees is about 1/4" in height. Good luck.
 

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Discussion Starter · #16 ·
OK, so I just lift the front tires off the ground, jacks under the frame rails, and put a c-clamp on the key to take all the pressure off of the screw and turn that however much to raise the front of the truck.

I'm ignorant on some of this stuff. I thought the torsion bar itself was somehow turned. I didn't realize it's just the small screw that you turn. Beginning to make sense now. Thanks.
 

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Just turn the screws

70 - no need to jack up or c-clamp anything, just a 19mm socket and good lever arm. I have a 2004.5 GMC Crew Cab LLY. I just put on Kumho's 285/75-16 KL-78 ($109/tire but still in the top five in survey results all other tires $140-180). I turned my torsion bar screws 4 turns, trimmed a little bit on the front air dam, thinking about zip tying the front wheel guards, and next step putting on some Bilsteins (I am going to get a set from Kennedy Diesel). Everything clears, truck rides great, Kumho's have awesome traction in the deep snow and they are quiet on the highway.

I like your 255/85 idea because they don't get too wide - end up floating in the rain & snow. I like the 285 Kumho's because they are only 8.75" accross the tread versus the 8" for the stock 245 Duravis 773's.

Good Luck
 

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you dont need a c-clamp. but before you crank i would measure each side center cap to fender and you will most likely find that the driver will be lower than the passenger. estimate 1/4" inch of lift per turn and crank however many turns you need to get the amount you desire. then drive the truck around the block and remeasure.
 

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Discussion Starter · #19 ·
OK, thanks a lot guys. Now to make my final decision on which tire.
 

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Makes bolt easier to turn if you unload it somehow...jacking seams safer than a C-clamp. I've heard guys here on this site saying you can strip the bolt if you dont unload it... Oh well...good luck with whatever you do...
 
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