Can a difference of one inch tire size slow down the truck

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Feb 22, 2011
I have a 1991 Landcruiser 3FE. Recently switched from a 31" tire to a 32" tire and now the truck doesn't like climbing up hills on the highway.

It seems to be happy at 45 mph and 80 mph and not happy anywhere in between.. I can go up the hill at 80mph just fine, but if I hit the hill at 65-70mph, it slows down to 45-50mph and stays there. Transmission seems to jump all over the place trying to find a gear it's happy in.

Is what I'm experiencing typical 3FE behavior or is this a direct result of the tire?

Should I go back down to a 31" tire?

Thank you in advance for your help.
That's life in the 3fe lane.
I am ditching the 31's to go back to the stock 235's due to this.
For some it's acceptable, climbing hills in first gear going 10 MPH is beyond ridiculous for me.

There are some areas I have to avoid due to not being able to haul that heavy pig up a hill.
You guys need to desmog, or at the very least do a major tune-up on your rigs. I'm running 38's. Have not regeared, and have no issue driving up hills.
I also don't expect my 160HP (on a good day) 3fe truck to be in the fast lane passing up traffic. If you want to drive like Schumacher, get a sportscar.
My 3fe on 37s and stock gears did just fine on the highway. Shift it into second when you need to. The engine will scream a little but it will hold 65 just fine. I think landcruiserphil posted a video of it a while back
All new plugs, wires etc, and valve adjust on mine.
Installed a new fuel pump sock and fuel hose at the pump. Drove around with a pressure gage to monitor fuel pressure and have adjusted the trans cable.
I may play with the emissions some to see if it makes a difference.
I've had plenty of BBC powered rigs and have played the 3.08 gears and 35's game more times than I can count and am fully aware of what a small IL6 will and will not do.
Keeping up with traffic would be satisfactory for me.
10 MPH is not going to cut it.
I don't expect to be doing 123 MPH up Rainier hill and passing 14 log trucks or doing 1/4 mile burnouts.
Most of the time I can time it right and maintain momentum and get on up.
If I have to pull a hill from a dead stop.. break out your lunch, it's gonna be a while.
Once it upshifts and gets out of the powerband it falls flat on it's face, all I can do is downshift and putt on up. That is unacceptable to me.
I'm still new to the Cruiser though and haven't discovered all the tricks yet so I may be missing something obvious but I don't think so.
It runs fine on flat to moderate hills with acceptable performance, 6% grades suck for me though.
Swap a Cummins 6bt or 6.5l Detroit diesel
Adjusting the kickdown cable and changing out the atf would be my next move if the engine is running really well. There's slso yhe option of a regear. Theres a guy local to me that does both thirds for $750 using Yukon gears.
Take it from someone who has 4.88's and 33's. The 3FE, 80 series is just going to feel slow and underpowered compared to other vehicles. We have the same amount of horsepower as a 4 cylinder Tacoma with twice the weight. Just downshift before you hit the larger hills and relax. If you're driving up mountains roads with any frequency, well, maybe you should look for something else or just accept that it's going to be a slow ride.
Down shift, down shift.
Can you downshift past 1st?
50 miles in second gear at 4500 is not doing the engine any favors.
All that nonsense to just run tires that are not matched to the gears is dumb.

Repower is an option, a costly and time consuming one.
Besides I happen to like the 3fe and at 166K miles it has a lot of life left to it.
Putting the rig back to factory specs and seeing how it does and address any issues is the logical choice for me at the moment.
There is a reason Mr. T put 235's and 4.10 gears in it.
Eventually it will have 33's and be regeared to 4.88. Don't need to pay anyone to do that as I am equipped and know how to set up gears and drop out members are cake.
But I am also looking for 93 on axles to swap into it as they have better brakes and a FF rear axle. I am not going to spend money on upgrading axles that will be swapped out.

I ran 39.5 Swampers on 3.08 half tons for a couple of months and it freaking sucked.
5.29 1 tons were so much better.
Doable? Yes, a huge PITA? You betcha.
1" in tire size can make a difference. I had a 90 4Runner with the 3slow engine in it. I went from the factory 31" Dunlops to 32" BFG MTs. That upgrade turned a marginal performer into a slug. Knowing what I know now, regearing probably would have helped, but eventually I went back to 31s.

Based on my experience, regearing may help.
I've had 3 other 4x4's besides the current 96 lx450 and currently also have a 4x4 frontier ( work truck ).... 89 yota pu,22re, 5:29's, 35's, marlin 4.7 tcase, etc., 98 silverado 350ci, 4:56, 35's, 86 diesel burban, 4:10's, 36's.... the best was the 89 yota ... before my current lx ! the problem with changing to any mod, is that you'll now chase fixes for the "fix" you just did. so with the 89 yota, was stock 4x4, then I lifted it 4", put 35's on and it was slow and had no power, had it regeared to 5:29's and quicklocks... and it was great for power, would still do 70 mph up any hill on the freeway , and wheeled great... but was expensive, and was always having to fix something on it . So unless your into rock crawling ( our 80's are too heavy, and I know people will differ on this , but to me their a brick ) the stock 31" setup is fine , it goes anywhere I point it up any trail, I don't rock crawl , cause it's dumb to me any more .... if you' rather spend your time wrenching and chasing down the next fix, fine , me I'd rather spend my time actually going places ... so my lx is for expedition stuff , camping , etc. it does well . I did do the stock height OME , cause the stock susp was saggy , took the 2nd and 3rd row seats out , for mattress laying down and less weight ( less weight = more power ) and just throw camping gear on top .... 31's are fine in my mind !

Here's my 89 yota and diesel burb ... can't fine the silverado pic ....and my current LX



That's life in the 3fe lane.
I am ditching the 31's to go back to the stock 235's due to this.
For some it's acceptable, climbing hills in first gear going 10 MPH is beyond ridiculous for me.

There are some areas I have to avoid due to not being able to haul that heavy pig up a hill.


So speed limit signs are more of a 'goal' for a 3F than a 'limit'?
Keep in mind that not all tire specs are equal. It may appear to only be a 1" difference in sizing officially, but check the actual specs. One tire might have been a smallish 31, the other a largish 32 and suddenly you're closer to 2" than 1" difference.
Also, gotta remember that load D and load E tires are much heavier. All that unsprung weight is a drain on what few horses we have left and does make quite a bit of difference.
Yes, I am re-evaluating my rim/tire combination. The OEM steelies weigh in at 38 lbs, and my 315 Toyo MTs I think weigh in at 68 lbs. That's 424 lbs for all four!

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