Meterpig

Oh the heresy! In all seriousness, the 4runner is used for majority grocery and motorcycle hauling duties. The truck came with 225/75/15 tires and now has 265/70/16.

Has anyone here put on 235/70/16?

The size is shorter, thinner and lighter. I am looking for a bit more power and greater efficiency.



My 4runner was built for 15 inch rims and tires. They were upgraded to 16 inch tires and wheels.

The factory tires:
225/75/15
28.3 inches tall
8.9 inches wide
29 lbs
741 revs per mile

The tires now:
265/70/16
30.6 inches tall
10.6 inches tall
Tire weight 41 lbs
Revs=679

The tires I am looking at:
235/70/16
29 inches tall
9.3 inches wide
35 lbs
718 per mile

So all in all, I am looking at 1.6 inch shorter tires which equals .75 actual lower height, but a loss in weight of 6 lbs per tire which is equivalent to one less tire or so.

Less un-sprung weight and lower rotating mass.

As you can see from the upgrade at the port, it lowered efficiency but raised the coolness level. Anyway, I checked with Costco today-they will do it since the door panel reads the smaller tires.

Matt16

Let us know how much fuel economy you gain. You have to calculate the actual differences travelled in though. For instance your odometer with small tires is going to read X miles sooner than with big tires.

L33T35T 4Runner

Just make sure your load index isn't any lower. If the stock 225/75R15 came with a load index of say 102S, don't go any lower than the 102. I'm not sure what is standard for a 235/70R16. Just make sure that load index number isnt any lower, this could be very dangerous.

Maybe check out a 245/70R16 to be on the safe side, or even just a 225/75R16. It wont be much taller than the 225/75R15

Jason - 5 year Master Tire Tech and Sales Specialist

scuba

Woah!!
this guy actually posts up here ! ^^

OH, OP, good luuck on your tire hunt.
and do let us know aboot the mileage factor


/me and my thread spamming

EDIT: Decide I had to add in this cause of my state of mind

L33T35T 4Runner

Tires are kinda my specialty Steve

scuba

wish I woulda known that before I shelled out 800 for 31's !
I sorta want 33's now...but thats not gonna happen till I get gears...


Stupid lonely friday night's


/my thread spaming again...

Meterpig

At 1984 max load per tire, that carries me well above the 5500GVWR. The load rating is above the 102 threshold on the LTX A/T 2.

The 4runner is a pathetic tow vehicle. When loading just a 300LB motorcycle on the tow hitch, you can really feel it. Add on a trailer and life gets fun.

I understand the thought of going bigger for a margin of safety so to speak. However, my goal is to go as close to stock as possible.

As for the speedometer issue, right now the speedo is off given that the tires are not stock. My MPG is is off as well without accurate readings. Right now it is off 2-3 MPH. Going closer to stock will return it to accurate.

I doubt there will be huge mileage gains. There should however be an increase in power to pavement.

john4r

I put 245/70 16 on as winter tires for my 98 4Runner. You don't notice much difference visually but it gets the tires in under the fenders width wise (just). I considered 235's but decided to be conservative. I think now that I have the 245s that the 235s would have been just fine.

What I wanted was a 245/75 which is the same height as the 265/70 but the tire I wanted didn't come in that size.

cackalak han

I'm curious if you're wanting to go small, why not put the stockers back on? 15" tires should be cheaper and definitely lighter than even 235/70/16's.

But in the end, I doubt you would see that much difference in MPG. Best I've got is ~23MPG with 265/70/16's and 245/75/16's. I can't see you getting any better than that. Even if it's slightly better, if you take the cost of the new tires, it would take you quite a while to make that cost up.

riverrat

My 4runner (3RZ 2.7L engine) came stock with the 15" rims and 225/75 R15 tires. I have 235/75 R15 BFG KOs on there now.

The 16" rims and larger (265/70 R16 I think) tires were an option on base model 3RZ runners like mine- this package included larger brakes (and also 4:56 gears instead of 4:10s). (I know that going to 16" rims would require me to get the larger brakes, so I am assuming that the reverse is true.)

If the OP's rig was upgraded to 16" rims, I'm pretty sure he got larger brakes too . So I believe that going back to 15" rims would require a retrofit to the smaller brakes, probably not worth it.

I'm considering going to 16" rims and the Tundra brake upgrade at some point in the future and have been mulling what size tires to get. I'd like to not have to regear and would also like to maintain decent power and mileage, which I need to think about since I have the 3RZ. But I'm not sure I want to go this route. I'm not a bigtime wheeler, mainly rough logging roads and snow. My runner is also a DD, so I'm not convinced the bigger tires and wheels are a good idea...

cackalak han

If it came from the factory with 16" rims, then he might have the upgraded, brakes, but his came factory with 15"s. Unless he did the brake upgrade himself, he can switch back and forth between the two sizes.

And just because you go with 16" rims, doesn't mean you have to upgrade the brakes. You can go from 15" to 22", if you wanted to, without changing the brakes.

riverrat

Hmm coulda sworn I read differently on here somewhere, but maybe not...I'm sure no expert!

Regardless, I'll probably try to upgrade my brakes at some point- the ones on there now (stockers with the 15" rims) are none too impressive. Could be a pad issue though.

Back on topic, I would also be interested in hearing about mileage and driveability is affected by changes in tire size.

cackalak han

Yeah, and only 4Runners came with the upgraded brakes. Tacoma's, even with factory 16's, did not come with the bigger brakes. And FWIW, I don't feel the need to change out my brakes at all. The key is like you said, good pads and good rotors. I just use Autozone Duralast rotors (blank) and their ceramic pads. Works great for me. But if I were to haul or tow a lot, I'd go with the Tundra upgrade.

Meterpig

Yes, the rims and tires were switched at the port or at the dealer-thus the sticker inside the door which reads 225/75/15.

I don't want to go back to rims as a)they are ugly and b)that is extra cost and zero benefit and c)no ability to upgrade brakes

And to one poster's point, the tires right now stick outside the fenders which is annoying. Again, this is my wife's rig which sees road duty and little off-road. My rig on the other hand, whenever purchased, will be in comparison, bad ass.

Texas_Ace

One thing to point out, going with shorter tires will actually lose MPG as you will be driving at higher RPM's. You wil gain accelration but lose MPG.

Now going to skinner/lighter tires will help all around except for grip.

Meterpig

Hmm, I don't think I will lose MPG. MPG is a function of fuel burn based on output, speed and drag.

My output will remain relatively the same, speed will decrease slightly but drag will decrease as well.

The rotating mass will decrease with the newer tires decreasing the load on the motor. It is interesting to note that some folks actually show no decrease in mileage with larger tires which means...they probably. are. It is a matter of physics.

Texas_Ace

True, and you will most likely even out the gains from the lighter and thiner tires but the shorter tires.

Fact is that at XXXXRPM you burn XXXX fuel at the very least. If you increase X then you increas the least amount of fuel you CAN use.

Going thiner and lighter is great but going shorter WILL cause you to lose MPG all else being the same. You are geared for the stock tire size. Now if you were to re-gear then you it would work.

Meterpig

Everyone knows that stock tires for my 4runner are 29.3 inches tall right? I don't know if that is clear. Right now I am running taller and heavier tires than stock.

I average, without speed correction, about 18MPG on the highway and 13-16 in town. I used to get 19-21-but that was before moving to 6,000 feet.

The question remains is, will the percentage increase in RPM's increase fuel burn greater than the amount saved by lower rotating mass?

Even if I stay the same, I will feel an increase in power. This will increase the tire revolutions which will assist in trailer and load hauling. Not to mention, the tires are cheaper.

The Costco guy did say that tire wear could increase given that the sidewalls were stretched out. He also said handling would decrease with more narrow tires.

Texas_Ace

Overall you will have more get up and go but your truck will be less stable then it is now.

Since you came stock with smaller tires then you are geared for them which means that going back to that size will indeed help. going shorter then it was stock will just raise the RPM's with no real increas in anything good except for get up and go.

Lighter, go for it, skinner, go for it. but shorter will only do good to a point. not to mention that 3rd gen 4runners look funny with anything under 30" tires IMO.

It is up to you but personally i would not go shorter.

Also, i bet the WAY you drive is a big part of your problem. You want the same take off speeds at sea level but at those higher Atl you use MUCH more gas to get the same power.

Also give your trucka full tune up, that will help a lot as well. Usually people get better MPG at higher ALT if you drive it easy.

You can also reset your ECU, that might help some as well, just un-plug the battery for 10 mins of so.

cackalak han

I think we all need to realize that there is a "sweet spot" for maximized MPG's. You can't go too small or too tall. Too small, and you're geared way too low and will suffer in the upper range. Too tall, and your engine will have to work too hard to maintain speed and will lose MPG's drastically. I believe the sweet spot for the 4Runners is ~31" tire (stock 265/70/16 or 245/75). I'd get a P-rated all-season highway tire in that size and call it good.

And I agree with TA -- 30" tires do look pretty puny on 4Runners.