Just to let Tundra owners know - You will be underpowered if you put on 33" BFG M/T's. I've got 255X85X16's. I've only been in mild off-road locations and they worked fine. In town I noticed no problems. Today I bucked a 30 mph wind on the highway and on very slight up grades I had to turn the OD off, as the mighty Tonka couldn't handle it! That I assume means they won't handle mild mud or worse except possibly in low range. I ordered a set of 456 gears - should be just fine after the install. First shipment of ARB bumpers for the Tundra came in last week. The front air locker is a couple of weeks away. (Define couple in Ausie?) <img border="0" title="" alt="[Wink]" src="images/icons/wink.gif" />

If your truck came w/ 31" tires and you jumped up to 33's, that's about a 6.5% increase in diameter.

Your truck probably came w/ 3.90:1 gears. The jump from 3.90 to 4.56 is about 17%. Way over-geared.

3.90>4.10 is 5.1% which would be a lot closer (doubt you'll notice the 1.5% difference from stock)
3.90>4.30 is 7.7% which would be pretty close too.

4.10's and 4.30's should be pretty easy to find in a junk yard on Tacoma's and T100 rears, and Tacoma and 4runner fronts... if you wanted to go the used route to try to save a little money.

And FWIW, I find it hard to believe a V8 Tundra is "underpowered" w/ 33's. Need power? Push pedal. <img border="0" title="" alt="[Big Grin]" src="images/icons/grin.gif" />

buy me 4.88s and i will give you my OEM 4.30s. i might even give you the lock right for a deal, so i can get an ARB.

I also thought the Tundra would have a lot more power then it demonstrated with the 33's. In stock form it never had a problem. After raising it 2" and putting on the M/TÆs, which brought it up another inch or so, and putting it's nose into a stiff wind the ole gal couldn't take it. It kept kicking in and out of OD on slight grades. The tire diameters are 30.7 for stock and 33.3 for the M/T's = .085%. I thought about the 430's first but changed my mind to the 456's for the little extra that it will give me while cruising in hilly terrain with the OD on and when bouncing along in 4H. I suppose when I get into some serious gumbo those 456Æs might test the front axles. <img border="0" title="" alt="[Roll Eyes]" src="images/icons/rolleyes.gif" />

I doubt you will break stuff with 4.56's, but your engine will be SCREAMING on the highway. You will also get pretty horrible mileage.

I am not sure whether you have a 4wd or a 2wd, but I have not heard of any gears for the front diff on the Tundra. You may want to look into headers to gain your power back. My friend has 33's on his Tun and it's still pretty quick. He also has the Tuff Country lift. I think I'll just wait for the RCD lift since it comes with a whole new spindle and not just a spacer for it.

BTW: What lift do you have? I have some spacers in the front right now with a set of Daystar add-a-leafs in the rear, but I have a set of custom coilovers being made by a guy in So Cal. It comes with a top conversion plate that converts the 3 bolts up top into an eye setup (similar to the camburg log travel kit) so I can run a Baja type Sway Away coilover with Heim joint (sp?) on both ends. He uses them on his Baja Trucks. I'd post a pic if I could.

<small>[ 07 May 2002, 08:12 PM: Message edited by: chris ]</small>

Do you think the change in tire size changed the shift points of the auto tranny? This OBD II stuff is all linked together...

The shift points seemed to remain the same. Driving on streets you could notice a little power loss but it wasn't bad at all, 4 to 6 inches of mud there was a very definite power loss in 2H while 4H seemed a little doggy. With the rear locker engaged it took a little more pedal than normal. The 456's are now in and I broke them in yesterday. Everything appears AOK -While in cruise mode the tranny shifted down one notch climbing a long 6 or 7 degree grade at 2K rpm - never came fully out of overdrive on that long grade or on shorter but steeper grades. In stock form it only down shifted one notch also but with the 33's it always kicked fully out of OD while in cruise mode. The rpm difference isn't bad either at moderate speeds. The speeds were measured via GPS:
Ratio Actual speed Odometer speed RPM's
390 60 58 1775
456 60 66 2025

390 65 61 1975
456 65 70 2200

390 70 65.5 2000
456 70 75 2350

390 75 70 2200
456 75 80 2500

390 80 73.5 2350
456 80 87 2700

It doesn't appear gas mileage will be much different at 70 mph and slower. After the initial cool-off period I broke the gears in between 1600 and 2200 rpms and just by judging from the gas tank marks I would guess that I won't lose more than 1 or possibly 2 mpg - I expect to take a bigger hit in city driving.