37 vs 35 opinions

Re-gearing your truck should be considered essential when going with larger tires. Can you get away with running slightly larger tires and not getting new gears? Yes. Is it ideal? No. When you change tire size, you essentially change the gearing of the whole drivetrain. And a hand-held programmer is not going to make it right. It may make the speedometer a bit more accurate, but it's not going to change the drivetrain.

Trucks/cars are made to operate at a certain powerband with certain gearing. When you change tire size, you should also change the gearing to get the powerband closer to stock. Otherwise, your powerband, shifting, MPH, MPG, etc, are all thrown off. I have a Hummer H2 on 40" Toyo's. When I changed the gears to 4.88's, it was a whole new truck. And according to a GPS, my speedometer is only 1-2 MPH off. Considering most speedo's aren't terribly accurate anyhow, I'll take it.

If you go with 37's, I feel that changing to 4.56's would be the way to go. It is important to note that with 4.56's, you won't have the off-the-line grunt as described above by the gentleman running 4.88's, but you WILL have lower RPM's while cruising. It is also important to note that as you go lower in gearing (higher number), you also give up a bit of strength in the ring & pinion because of the number of teeth. The gear sizes discussed here won't have this issue, but when guys go with 5.13's and up, this is always a concern.

Hope this helps.

Charles

G & P Racing said:

If you are going to offroad it hard then you are going to need glass, I went with glassworks, and you are going to need to cut back the firewall. This has been discussed a lot and you should be able to search out a lot of info.
The gears were G2. I agree with Tbone, if you are running offroad going with 37's and doing the correct mods you will never look back.

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That's not true. It depends on which 37s you go with and whether or not you have stock wheels. I have stock beadlock wheels and 37s and don't have glass. I offraod my raptor as hard as possible and I've only rub-touched the liner a few times. I did trim underneath though.

Agree 100% about the 4.88 gears. Great mod

You are very correct that wheels make a big difference. I have never played with the newer stock beadlocks. My rigs a 2011, run Method beadlocks, both the old and new style with a few different 37's. General Grabbers, BFG KR and KR2...all would blow the stock liners at full bump. Cool to know the stock beadlocks work! I do like the look of wider glass and plan to do the bedsides to match at some point.

Does anyone have the part #'s for front AND back pinion gears (4.56's) when running heavy Toyo 37's? If I can lower my rpm, and get better performance off the line than its a win for me! I'm getting 9.3 mpg strictly bc I'm always on the throttle waiting for the stock powerband to come into play.......for a couple years, this lesser power running Toyo 37's didn't bother me but times changed.

^^ Just call Randy's Ring & Pinion.

X2 on Randy's Ring & Pinion. They have done a couple of rigs for me and really know their stuff, including installing 4.88's in a 2011 housing when some folks said it could not be done because of the bearing size changes. That setup had done the NORRA 500 and 1000 with out issue. They support a lot off rock crawler and KOH guys, and are a great member of the offroad community.

Granted, I'm fairly new to Raptors, but I've built many an offroad vehicle. The issue with 37"+ tires starts with fit and power, then usually ends with premature wear on components. Just food for thought.