3.70 gears & Tire Size

Sep 3, 2003
I am interested in putting some bigger tires on my 1979 FJ40 as part of my frame-off renovation. Was thinking about 12.50 x 33 Super Swampers SSR on 15 x 8 wheels. I have a 4" lift kit from TPI. But a buddy of mine said he wished he had gone with the 35" SSR's.

Do you guys have an opinion or experience in running 35" tires on the 79 or later Landcruisers which have the 3.70 differentials? Do you think it would work, or would I have to regear the diffs with 4.11's or even lower?

I was thinking about going with the 35" SSR's and doing a Saginaw Power steering conversion for greater strength, but a friend mentioned the existing 3.70 differentials might not work too well with the larger tires. And that I would probably have to change out the differential gears to be happy with the performance with that large a tire. I would probably just go with a Mini-truck PS conversion if I went with the 33" tires.

Any opinions would be appreciated. Thanks a lot, appreciate all the information on this board.

Jim D.


On the way there
Mar 15, 2003
Sacramento, CA
What your friend says is true. 33's with 3.73 gears will be very borderline, let alone 35's. To run 35's you should regear to at least 4.56. 33's work well with 4.11's. 3.73's and 33 inch tires actually works well cruising down the highway but it sucks pulling away from a stop light especially if there is any uphill grade. For off-road use, the lower gearing, the better. If you are going to the trouble and expense of a frame off resto, spend a few more $ on proper gears.


UP of MI.
Jan 28, 2003
UP of Michigan
It depends on what you use your cruiser for. Off road, or daily driver, or a little bit of both. I would say you'd be happy with 33's for every day driving. 35's, it's tough to say, but I would recommend a 4:11. I just pulled my 1970 axles that have 4:11's in them, front and rear because I went with GM axles under my 40. If you're close enough to Pensacola, FL let me know if you'd be interested in them.
Mar 14, 2003
Gig Harbor WA
I'm very happy with 33's(9.5's) with the 3.70's on both my 82 fj40's, i feel no need to re-grear, 35's yes 4.10 or 4.56's.

John H


Apr 13, 2003
Ridgway, CO
You could easily switch your 3.70 3rd members with 4.11 3rd members, it would probably be cheaper than regearing, but if you've got the $$$, go with the 4.56 regear.
Mar 27, 2003
Georgia Tech
Hey Jim! Bailey here...
You don't want the SSR's you want the TSL's like mine remember? :D
With my 4" lift, I feel that the 33"s are perfect, they look good, and still leave room for flex, I have cut fenders as well, I don't know if yours are cut, I would assume no on a frame off, and if they are not cut, 35's may not fit as well. If I were you I would go with 33's and no regear, that will give you excelent highway gearing, the one thing that bugs me the most about my cruiser. Any larger than 33's and I would swap in some 4.10 pumpkins.

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