I will be running 37" tires on my 86 4Runner, and i have duel cases, will 4.88 gears work ok for my set up ?, i know 5.29`s would be better but i just don`t have the money for that right now.

 

It depends...

Search, read, this has been discussed to death. It all depends on what you want out of your rig.

 

Yes it will work. But it will work better with 5.29's. Plain and simple.

 

Trail only or will you be driving it on the road?

Auto or manual?

 

I will be driving it on the road some, it has a manual trans with duel cases.

 

31"-4.56
33"-4.88
35"-5.29
35+" 5.71

I think 4.88s are going to be brutal with 37" tires.

 

My truck was an automatic (now manual) so it has 4.30 gears now, so i would think that 4.88 gears would be a hell of an improvement over the 4.30`s ?.

 

No they wouldnt..

 

I guess it cant be to much worse than 33's on 4.10's

 

13% difference, which is not much.

5.29 would be 23% difference, which is a bit better. And the price of 5.29 gears is the same as 4.88 gears.

 

Oh yes, it can be much worse. You'll be taking the engine out of its torque band. Let me give you an example. I had 31" tires with 4.10s. That's actually pretty common and accepted to be fine. Factory 31s came with 4.56 (5spd). There is a particular hill near my house about a kilometer long and a pretty steep grade, with 4.10s, the fastest speed I could maintain was about 70km/h, I regeared to 4.56s and now I can come out the top at 100 km/h.

The gearing advantage is only about 10%, yet I was able to see an increase of 30% in terms of speed on this hill. This is because the engines in our trucks have pretty narrow torque bands and the gearing from the factory is calculated to make the most of the torque/ power available.

Why not do an upgrade you can afford to do well.

 

I see top speeds in the 40's in your future. Offroad with two case you'll be golden.

 

i dont understand why you wouldn't get 5.29s unless your getting the 4.88's for free? you say you have 4.30's now so that means your yet to replace them, why not replace them with what's best if they cost the same?

 

5.29s are not enough for 37" tires. You need to go all the way up to 5.71. Not only to you have to deal with the large diameter tires, but there's the mass of those meats to contend with. Interco says the 37x14R15 weighs 69lbs. The 31x10.5r15 BFG T/A KO weighs 43lbs.

Given that 1lb on the tires is equivalent to 10lbs added to the body of the truck, going from a 31 to a 37 is 26lbs difference per tire which translates into and extra 1040lbs your hauling when accelerating. Gearing needs to compensate for that as well.

 

4cyl or v6? If you have 22re, you will most def want 5.71.... you might be happy with 5.29 on v6...or only slightly unhappy with 4.88...but if its a 4 cyl.... you want the 5.71's. just My opinion.

 

5.29 is perfect IMO for 37's, street and trail, 4 or 6 cyl.