2.7L with 3.91 stock gears. Tire size experience?

Hey all, I am kicking around ideas for my next set of tires.

Currently running stock 235/75/15 (~29.5") tires, but they just look small in the wheel wells. I want to go a bit bigger, but nothing crazy. The truck is already slow on the hills.

I was pretty dead set on 235/85/16 as I have read a lot of threads on here about how much folks like that size, and I really like the look. But, after looking up my diff. code on the door sticker I found that I have 3.91 gears. Paired with the fact that the truck is already slow, it makes me a bit nervous to go to a heavy (Load E, ~47-52lbs each) ~32" tire.

Anyone else out there running a 235/85/16 with 3.91 gears and the 2.7L motor? How does the truck handle it? I would love to regear to 4.56 with lockers and all that but that is not an option financially.

I am now leaning towards a 245/75/16 (~31") Load C (seem to run ~40-45lbs each) after looking into it a bit, but figured I would ask here and see if anyone has experience with oversize tires on the 2.7 with 3.91 gears.

I did search through a lot of posts here but did not find a thread specifically on this engine and gear combination so figured I would post the question.

Thanks!

 

Manual or auto? I had the same dilemma but even worse gearing - see https://www.tacomaworld.com/threads/95-5-ex-cab-4x4-mlh-5-speed-mt-tires-dilema.399194/

I also originally had 235/75/15 (M/S) and they indeed look silly small. My speedo was also off too. Because I was limited by the rim width (6 inch) I went for BFG A/T KO2 size 30X9.5R15LT. They are not very much bigger but they look bigger. Now speedo is very close to real, I did not loose any mpg (besides tire diameter correction) and no visible loss of acceleration. But I have manual, so while I can't put 5th gear below 50mph the 3rd gear still kicks ass.

With Michelin 235/75/R15 M/S



With BFG A/T KO2 size 30X9.5R15LT

 

Regular cab power, brother! I had 235/85r16's with the stock 4:30 gears for several years. I know it's not exactly what you're asking for but might be as close as you'll get. It was a great combination that was decent for highway speeds and 4-Lo creeping without much of a MPG penalty over stock. Though with the 2.7L it still ran out of steam on long inclines. Now I have 255/85r16's and 4:88's which I already like better. 4-Lo feels much lower, highway RPM's are not much higher, and I don't care about MPG anymore.

What you could do since regearing is not in the budget right now, is get some P-rated 265/75r16 all-terrain tires. There are several that weigh under 40 lbs. per tire, like the Goodyear Wrangler Trailrunner AT and the Cooper Discoverer AT3 4S. Those would fill the wheel wells nicely without too much of a weight penalty.

 

@RysiuM Thanks for the comparison. I actually picked up a set of used 16" alloy wheels for $60 on craigslist to use when I get around to new tires. My stock steelies are getting really rusted where the spokes meet the bead.

@DJB1

Thanks for the reply bud. Love these little Regular cab 1st gens! I have to admit that I have stalked your build page and really love your truck. Wishing that I had the 4.30 gears stock in mine!

I have considered the 265/75r16s, but from what I have read the size makes more of an impact on power loss than weight. Though to be honest I have no personal experience with changing tire sizes (yet). I am leaning toward an LT tire just for the sidewall strength while out in the boonies and aired down. I like Goodyears Duratrac, which in 245/75r16 load C is right at 40lbs.

 

Oh @RysiuM, mine is a Manual. Forgot to include that in the reply.

 

The good thing with that gearing and M/T combination is that you can cruise on 5th with very good mpg and if you need acceleration you can downshift straight to 3rd and have plenty of of speed to gain before the red line. And if I need more low speed torque I can always switch to 2L (that is 4L without engaging locks on front hubs). I use it quite often lately towing dead trees on my property.

I never understand people saying that 2.7 is lacking torque. I guess they have A/T or they don't know how to downshift and lagging the engine till rods pop out.

 

Yeah I have never had a problem with low speeds. Only trouble is getting up inclines. Especially at elevation. I could barely maintain speed in 3rd gear going up the west side of Vail pass in CO last summer. Though that is well over 10,000ft with up to 8% grade in areas.

 

Nice Ride!

 

Thanks @96degreesindashayd!

Back at you. Always loved the look of the pre-facelift 1st gens and pickups.

 

Those 235's are more like a 28.9" tire, not 29.5". I know, that's "only" half an inch, but that can make the difference if your tire size puts you on the fence between re-gearing or not.

I would say that if you're *already* complaining about the lack of power you have with the stock size, the larger tires (ANY larger size) will only make it worse.

With a v6, the gearing is "less" important with bigger tires, since the higher HP and help compensate, but the 4cyls need more help.

I'm going to venture a guess that you'll end up regearing...

 

Yeah, this is probably the cold sober advice that I need to hear on this. And good catch on my tire size mistake -- I knew I should have looked it up to double check before guessing.

Re-gearing would be totally appropriate, and really the "correct" way to go about this, but I really don't have multiple thousands of dollars to spend on those kinds of mods for this truck. With 252,000 miles on it I have plenty of things to upkeep just maintaining it in good running order.

Tacomaworld tire calculator does have the 245's on the low range of stock ratios when compared to the 235's with 3.91 gears, though. For what that's worth.

Wish I could throw a set of tires on it just to see what it felt like without a $1200 price tag, though.

 

What, you don't have a money tree in your back yard???

Are you 4x4 or a pre-runner? From your avatar pic it looks to at least be a 6 lug...

There are ways to cheapen the cost of a complete re-gear. Like finding a complete diff/axle assembly from a wrecking yard, and selling your current one. That may help offset the cost, rather than re-gear your current diff(s). Used parts with an unknown history do have their own set of risks, though...

 

Dude I have been burying my spare change for years... Never gotten anything to sprout though. Must be in the wrong climate! Ha

I have a base model 4x4. 5-speed manual. Totally stock except I modified an old trail gear tube bumper from a pre-95.5 pickup to fit the rear. And put a front hitch on for a quick connect winch.

Yes used parts are tough. I have a tiny tiny garage too, and don't have much experience really tearing into large projects like swapping the whole axle assembly. Especially the front end stuff.

I have done a head gasket and manual trans swap on a 97 eclipse, and auto trans swap on a 95 grand prix. But that was when I had a lot more space and some really good and knowledgeable friends to help out. I have moved states several times and lost proximity to my grease monkey friends. Someday maybe I'll find another crew.

 

Replacing diffs are pretty easy. Mostly just bolt on stuff. Rear is a no-brainer, all you need is some jackstands tall enough to hold the frame up. For the front, same kinda deal, the main thing is draining the diff fluid and removing the CVs (they pretty much just pop out).

If you've done a head gasket and a trans swap, this should be easy peasy.

If you run into trouble, that's what this forum is for.

 

I have 265/75/16 heavy Coopers, 2.7 auto and it drags ass on hills. My truck (yours too I imagine) is geared high to begin with, 30-35 mph is tough, it can’t decide what gear to be in.... if you stay with a passenger rated tire you might make out better than me

 

2.7 and Auto is very bad combination for any tires and gearing. Fortunately OP has Manual transmission and that gives much more flexibility on driving. Yes, driving uphill especially on high elevation even on 3rd gear may drag, and 2.7 is not the best for that environment (manual or auto). I was really surprised when the first time I was going over Tioga Pass in Yosemite learning how 9000+ ft elevation impacts the performance of natural breathing engine. But then if you know the limits just take your time and stay on the right lane - learn from truckers .

 

When I went from 235/75/15 to 31/10.5/15 my base 2.7 manual truck was noticeably slower in off-the-line acceleration. BUT- it still will boogy on the highway at 85, every once in a while if I want to maintain speed I have to drop a gear on a hill. Not a big deal. The trade off for me was absolutely worth it. If I want to go fast I hop in my tuned up turbo euro hatch...

 

@paetersen Thanks for the info. Do you happen to know the gearing of your truck? Or just post a pic of the door sticker with the axle code and I can look it up. Your truck is really similar to mine. Even down to the 20yr old extra height restored topper .

Before:


After

 

3.91

The only reason I really want to regear is to get a selectable locking rear diff. Which tbh is most likely never gonna happen as a tube front bumper + winch is still much easier and cheaper than sourcing all the parts for a regear and will pull you out of any situation that open diffs got you stuck in.

I also never deal with altitude over 5000. The bulk of my driving is from sea level to 3500 so you might want to take that into consideration if you drive at higher altitudes.

 

Awesome. Thanks for your feedback. Exactly what I was hoping for. I don't live in CO anymore so will only encounter really high elevation on road trips. Lots of hills on the Palouse in North Idaho, but can always down shift and crawl my way up.

I am in a similar boat on the re-gear. If money was not an issue I would love selectable lockers and 4.56's. But I have a hitch mounted winch if I really need it and the $$$ for serious offload mods is just not realistically in my future.