I run 285 BFG AT's for everyday use and 305 MTR's for off-road use (17" wheels for both). The power difference and ride quality between the two isn't all that much, but I do have a Magnaflow exhaust and the TRD CAI that gives me a bit more power. I just re-geared to 4:10's (from the OEM 3:73's) and I'm still in the break-in phase so I haven't punched it yet to see what it'll do. I can tell that it does have more acceleration off idle, but until I get another 200 miles on it I won't be able to discern how much more.
I love the sight of the Fj lifted 6"with at least 35's! I have to drive aggressively with all the idiots and traffic here. Yes you will lose some mpg's and a little power,but not much! What you gain Is unreal in terms of wheelin off road and in conditions of Ice,snow,sand,mud and lookin down and over the H3! I would not waste the time or money not to do it right the first time, I too went the route of so called spacers and leveling kits and to some 33"s I Did not get much performance or looks for that matter. Be the first in your area to do it right, then enjoy what the Fj can really offer! I run the Nitto all Terrain Grapplers 325-60-20"s There rated #1 look it up.
It's my understanding that the dealership can simply reprogram the PCU for tires up to 33" (or poss even up to 35"). If that's the case, why would you need to regear? Also, I just recently lifted and upgraded to 295/70R17 Nitto Terra Grapplers but have not been to the dealership yet. Will driving it in this condition cause any damage based on shift points being off and what not?
Reprogramming the ECU will correct for ABS / A-Trac / and speedo readings, but will not compensate for the additional driveline stress from the weight of the larger tires and wheels, or from the lowered rpm range the vehicle drives in with larger rolling diameter meats on it. Regearing allows the engine rpm range to return close to stock (usual choice - although you can regear for higher / lower ranges if you choose), so the stress of starting up larger tires doesn't back up into the drivetrain. Remember, you don't actually lose power, its just not released through the tires. This horsepower gets unloaded on the crank, trans, t/c, driveshaft, diff, etc. - regearing help to lighten that stress load, while reprogramming corrects the electrically activated circuits...
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Well I decided to go with the Moto Metal 951's (17X9). Still undecided about the tires but still leaning toward the 305's as discussed earlier. All the aftermarket tires I've looked at (285-305) weigh 55 to 64 lbs. The 305's are in the middle of the pack weighing in @ 60lbs. The problem is the stock tire Toyota came up with for the FJ weighs 37 lbs. This makes all aftermarket tires power robbers. So -- as someone else said--guess I'll just keep the stockers for long trips---who knows.
Reprogramming the ECU will correct for ABS / A-Trac / and speedo readings, but will not compensate for the additional driveline stress from the weight of the larger tires and wheels, or from the lowered rpm range the vehicle drives in with larger rolling diameter meats on it. Regearing allows the engine rpm range to return close to stock (usual choice - although you can regear for higher / lower ranges if you choose), so the stress of starting up larger tires doesn't back up into the drivetrain. Remember, you don't actually lose power, its just not released through the tires. This horsepower gets unloaded on the crank, trans, t/c, driveshaft, diff, etc. - regearing help to lighten that stress load, while reprogramming corrects the electrically activated circuits...
Hey Larry
First I want to say thanks for your inspiration to create a storage box for the back. I built mine and need to wait for the weather to warm up a bit to finish the moldings. Once I am done I will post som pics
Second, I am having the dealer install the ARB Bumper (No winch), OME Medium Kit and 275's. Should I be having them reprogram the computer for this?
Thanks
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Last edited by fourx4ord : 02-22-2008 at 12:22 PM.
Reprogramming the ECU will correct for ABS / A-Trac / and speedo readings, but will not compensate for the additional driveline stress from the weight of the larger tires and wheels, or from the lowered rpm range the vehicle drives in with larger rolling diameter meats on it. Regearing allows the engine rpm range to return close to stock (usual choice - although you can regear for higher / lower ranges if you choose), so the stress of starting up larger tires doesn't back up into the drivetrain. Remember, you don't actually lose power, its just not released through the tires. This horsepower gets unloaded on the crank, trans, t/c, driveshaft, diff, etc. - regearing help to lighten that stress load, while reprogramming corrects the electrically activated circuits...
Thanks for the response, Larry. Out of curiosity, how much does regearing an AT normally run on average if I wanted to get it close to stock? Is the amount of added stress enough that I should be concerned about getting this done asap?
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Re: Loss of Power w/ Increase Tire Size
Yes it does... and big time on some vehicles.. Coming up from jeep Wranglers I now have more brake than I can deal with. I'm having to learn to just press lightly.. Ron
Quote:
DEWFPO previously said:
One other point that I don't see mentioned is that braking also degrades the larger the tire.
DEWFPO
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One other point that I don't see mentioned is that braking also degrades the larger the tire.
DEWFPO
I've not experenced that... with any of my trucks. Only problems I have seen is if you go larger that 35". I try to speak from experence, not speculation.
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