What tires vs regearing?

Tire question, apologies in advance if its dumb.

When exactly do you need regearing? Is it purely based on the tire weight? (No steel bumbers, drawers, nothing)

1)Hypothetically if you get tall tire with the thread width almost same as stock assuming the weight is similar, running at exact gps speed, let's say 75mph will the engine feel any difference? (Or feel lack of power)

2) If you get this 34in tire almost same width as stock and just 15lbs more per tire will it feel better than running something like Falken Wildpeak 275 that are 58lbs per tire?

• dunlop grandtrek at20 P265/70R17 113S SL - 40 LBS (stock)
• toyo open country at iii 34 X10.50R17 LT 120S D1 - 55 LBS
• -falken wildpeak at3w LT275/70R17 Load C - 58lbs..!!

 

You don’t need to regear with any of those sizes, and I doubt you’ll notice much difference

 

I went down to a 245/45 ZR20. I picked up torque it was a lot smoother and it lowered it a little.

 

I do notice a little with Falken Wildpeak 275s feel like a big 285.

 

If you live where it's flat, you may not "need" to regear at all. It's subjective, and depends on how much acceleration loss you can deal with.

Typically it has to do with the height of the tire. Tire height is an aspect of your overall final drive ratio, a taller tire is effectively lowering your final gear ratio.

Stock 4R gearing is 3.73, going to a taller tire can be the equivalent of going to a 3.23 gear. The lower the number, the more torque/energy it takes to turn.

The lower final drive ratio equates to lower engine RPM at any given speed. We know the 4.0 makes power at higher rpm, so this is far from ideal. (Some argue that even stock, regearing is necessary for this reason, esp on the Tacoma). Since the engine is now operating outside of it's designed RPM range, performance suffers.

This is when regearing comes in Going to a 4.30 gear with 34" tires may be the equivalent of 3.73 with stock tire height, bringing the engine back into it's ideal operating range, improving drivability.

It's like gearing on a bike, the larger the (front) chainring is, the harder it is to pedal. Shift to a smaller gear, it gets easier.

 

@Trail Runnah,


If I'm keeping the weight closer to stock, width closer to stock (so assuming no extra traction added) still it needs more torque/energy it takes to turn? To keep same gps speed need less rpm (me thinking about the bike front gear)?

(Another reason behind this is I cannot run 285/70R17 on my TRD Pro wheels )

 

I’m on e load 295’s and don’t feel a need to regear.

 

Weight and width doesn't effect overall gearing, only height.

Extra weight DOES effect performance negatively, but it does not effect gearing.

Like I said, you don't HAVE to regear. If you're satisfied with the performance of stock gearing with larger tires, go for it. It's not going to destroy the vehicle, but your speedo will be off a bit.

And yes, numerically lower gearing = less engine RPM for any given speed. So instead of turning 2,000 RPM at 70 you're turning 1700 with the larger tires. Not a big deal in flat terrain, but when passing or climbing hills your engine will work harder because it does not make much power at low rpms. The transmission may downshift an extra gear, and more often.

If you off-road, this also effects crawl ratio while off-roading. Serious off-roaders building trail rigs go the opposite way, numerically high gearing that can dramatically increase RPM on the highway, but allow for much more torque and control on the trail. (For example going to 4.88 gears and turning 3,000 RPM at 70).

 

Thank you @Trail Runnah for sharing the info. Really appreciate that.
I was reading and trying to get more info too and have plenty of time before I decide. For sure weight will not be a big deal as right now with 265s (45lbs each tire) I'm at 5000lbs and these 34s are just 55lbs, just 40lbs unsprung mass difference. Have to figure out height impact.

https://trail4runner.com/2019/07/18/regearing-4-56-gears-5th-gen-4runner-review/

 

Glad to help! I hope all that made sense.

Research is good, none of these mods are cheap and mistakes can be costly!

One thing to note as far as the tire weight, it's not the unsprung weight that's the big deal, it's the ROTATING mass that is. More rotating mass is harder to start and stop rotating.

 

Yeah the 8x multiplication

 

As mentioned above, I think it really comes down to your use and environment.

My Toyo 285/70/17's (C) are around 55# apiece, and I don't really ever feel like I need a regear with them. The only time you really feel a difference is when you try to accelerate briskly. In normal acceleration, they are fine.

My 295's (E) also don't feel bad for normal driving. But, on the freeway, it downshifts a lot. Most of the time I keep it in S4, even on the freeway. It also feels pretty slow trying to pass, or getting on the freeway.

Like @Trail Runnah mentioned, you also notice the difference when crawling. If you like to use 4Lo and S1 to engine brake on steep descents, you'll be using the brake pedal more than you do on the OEM tires.

 

To be honest, I'm probably at where @Thatbassguy is. I'm running stock size right now, considering maybe going up at some point, because I'm pretty certain I'm going to lift it pretty soon.

Not sure if I want to do a 285/70, or a 255 80 17. Both are 33ish inches tall, but the 255 is about an inch and a half narrower. I imagine both will be around 55ish pounds.

I would like to re-gear, but that simply not in the budget right now, and with the amount of highway driving I do, I think I would probably lose even more mileage. I think going up maybe to 4:10 would get you back to the stock ratio, but that hardly seems worth the expense.

If this was mostly a trail rig, I probably would want to go to a 34 and re-gear to maybe 456.

 

@Trail Runnah the reason I look at this Toyo 34 X10.50R17 LT 120S D1 is because they are not far from the weight department, only 55lbs. And they are not Load E (wish they had Load C option for better on road comfort). And they are not too wide for my TRD Pro 17x7 wheel, 10.5 = 266.7mm and not too narrow to look odd on a newer body style vehicle like a 4Runner. Toyo's having 3pmf rating is a big deal for me too. So if could find they don't feel sluggish on stock gearing it would be damn perfect for me but at a higher tire price tag.

 

That actually sounds like a perfect tire, I didn't know they had it available on that size. I would probably consider that one myself. I like the 10.5" width, personally I don't t really like the look of a wider tire. Another bonus with the narrower tire is that it's less likely to rub, so you have less of a chance of needing to do the body mount chop.

A lot of people increase tire size without regearing, you'll probably be fine. But like I said, it all depends on how much loss of performance you're okay with where you live.

I don't think I mentioned earlier, the bigger tire will also increase your stopping distances, as that extra rotating mass and diameter takes more work to stop as well.

 

Whether or not it's "okay" really depends on how one uses their 4Runner.

If it is not "okay" to keep the stock gears with added weight and bigger tires, then it's probably also not okay to tow without regearing.

I have about 500 lb of added permanent weight, and usually drive around with at least a hundred pounds of recovery gear and camping gear, etc. I run 285's and 295's. And, yet, I have no problem getting where I'm going. 87,000 miles on my 4Runner, and no issues.

Also, regearing does not negate the added stress on the suspension components and brakes. The added wear and tear is just something you have to live with. Otherwise, if someone wants to modify a vehicle for off-roading without any concern about added wear and tear, they probably should start with a different platform.

 

I think most of us are aware that our bearings, CV axles, ball joints, brakes, etc. are going to wear prematurely. Anyone who isn't comfortable with that should definitely stick to the mall parking lot.

 

I think some of that will come down to driving style. Driving aggressively on oversized tires, or towing/hauling will definitely put a strain on things.

I think that as long as someone recognizes the added strain they're putting on everything, and drives accordingly, they will be fine. Obviously, wear and tear items are going to wear out sooner. But, I don't think some extra weight and bigger tires are going to send a vehicle to an early grave.

However, I'll say that 295's are definitely pushing it without a regear. And, I don't think I'd go to 35" tires without regearing.

 

Plenty running 315’s without a regear

 

I think this would suck. (At least for off-roading)

Anyone on this forum?

 

iunno, but I may let ya know here soon

285/75 is 60lbs. 315/70 is 67lbs (toyo)

my grapplers are coming to an end, so about to make some kind of jump

 

My 285 Toyos are 55# (LT/C). My Yokohamas are 64# apiece, and pushing it on stock gears. Add in another inch of diameter, and I think it would suck.

 

I already have LT/C 33's (285/70/17) and LT/E 33.5's (295/70/17). I am fine.

 

Not really. 4lo would suck, also. In 4lo, I use S1 for engine braking. Even with 295's, it's not great. With 35's, you'd be riding the brakes nonstop on descents.

 

Agreed! That's why I won't be going any bigger without regearing. I also haven't said that one shouldn't regear for 33's, just that it's not mandatory.

 

Turns out these have a fairly poor crawl ratio to begin with. I recently looked it up, it's around 33:1. For comparison, the other day I was looking up Land Rover LR3 info for kicks, and the LR3 has a 45:1 crawl ratio.

I was at an off-roading event 2 weeks ago, I got to talking to the organizer. He's a Rover guy, and not gonna lie he was doing a good job of selling me on the LR3 as a budget overlander/trail rig. They sound great, but not sure buying a 15 y/o JLR product is very prudent, lol.

 

I’ve toyed around with the idea of regear for a years. It’s one of those thing though where it’s a big price tag for unknown results. A guy I work with has a modified 5th Gen on 285s. Not a huge tire and his build doesn’t have a while ton of weight added but definitely has some heft - molle racks, roof rack, slimline steel bumper, sliders, armor, winch, fridge, no drawers and stock rear bumper. He just finished the break after having it regeared to 4.56 and had me drive it to take us to and from lunch and I was immediately sold the regear. Night and day difference in drivability, it just felt so normal and nimble. Blew my mind how significantly better it felt.

That convinced me. I’m on 33.3” tires, I have a bunch weight, my Limited has some extra drivetrain lose from being full time 4WD, I live at 5500’ above sea level and most of my recreational time is 8000’-12000’ above sea level, lots of uphills, and it’s not a daily driver - All things considered I’m regearing to 4.88:1, parts are ordered.

 

If you haven't yet, do yourself a favor and get the kdmax tune... its no joke.

315 70 17 goodyear territory are c rated(stock bronco tire) and weight 54lbs.

I honestly don't go offroad enough to even consider anything other the a sl rated tire.

 

I would wait for 60 months/60,000 miles warranty if I go engine tune route. Not comfortable to take risk anything goes wrong with even something else having to go to dealer and they put the blame on tune when under warranty. After warranty period, yes will try. Until that would like to just play with suspension & careful tire selection game. This post is to see if I could stay away from regearing.

I like to keep stock look, so with TRD Pro wheels I cannot go 285 or wider. So 315 is out, also don't want bmc but ready for a little bumper cut and push tires forward. Why I looked at 34x10.5 which is 266.7mm wide tire. Would be nice to have Load C option but 34x10.5R17 are Load D. Have to test drive and see. One of my friend have Duratrac 285/70R17 Load D, so will see how the on road feel of Load D.

 

I'm pretty sure the tune is "hidden" to the dealer.

Lightweight wheels and light tires such as sl rated.
There's plenty of wheels under 23lbs. 2857017s sl are in the 45lb range. The lighter the better.

Do you have a reason to go bigger then 285 70 17?