33's mpg vs 35's mpg

[Quentin18]

i was wondering, how much of a difference in gas mileage would there be between 31'' tires 33'' tires and 35'' tires.
im wanting to atleast do 33'' tires but i think the 35''s look way BA and i know it will be a lot better off road but what about the MPG? will it basically be crap if i put 35''s or will it not be much different from 33''s?

[Herbicidal]

If you go to 35's you'll need to regear otherwise you will cook the tranny. With 4.88's, on the freeway at 70 mph the best I get is just 15 mpg. Around town, it's more like 13.5 to 14 mpg. Towing a 5,600 lb travel trailer: 8 - 9 mpg. My truck is heavy! Last time it was on the scales it was almost 6,000 lbs! The extra weight comes from the front mounted winch, hi-lift jack in the bed, heavy duty skid plate, larger tires and the stouter components from the RCD lift. The more weight, the worse the fuel economy. Oh well, I didn't buy the truck for good gas mileage, that's why I have a Yaris now.

[Quentin18]

k this is the problem i have with the mpg in tundras. the paper that came witht the truck claims 15 city 18 highway but i dont even get like close to 15 city its more like 13 and when im on the highway i got like 15-17. but then i hear ppl claim that there truck gets like 17 in the city and like 22 highway. i dont get it. is like something screwd up with my truck?

[Herbicidal]

It totally depends upon how you drive. Don't go more than 5 mph over the speed limit, especially on the freeway. If you ease away from stop lights/stop signs and don't go over 3,000 rpm when you're doing it, you should get decent mileage. I tried to do that and I was not always able to. Having a v8 is too much fun!

Your truck also has to be in a good state of 'tune'. Good spark plugs, clean air filter, correct tire pressure, no extra weight in the cab or bed, etc. I'm running Amsoil synthetic in the tranny and Mobile1 synthetic in the engine.

Sounds to me like you're getting gas mileage similar to most people when they use the truck like a truck.

[Jwitz]

i get 16.5 to 17 going 75 with 33's... i think it's the advantage of 4.10 gears that come with the v6... and the v6

[Quentin18]

Originally Posted by Herbicidal

It totally depends upon how you drive. Don't go more than 5 mph over the speed limit, especially on the freeway. If you ease away from stop lights/stop signs and don't go over 3,000 rpm when you're doing it, you should get decent mileage. I tried to do that and I was not always able to. Having a v8 is too much fun!

Your truck also has to be in a good state of 'tune'. Good spark plugs, clean air filter, correct tire pressure, no extra weight in the cab or bed, etc. I'm running Amsoil synthetic in the tranny and Mobile1 synthetic in the engine.

Sounds to me like you're getting gas mileage similar to most people when they use the truck like a truck.

Ya i actually use my truck like a truck. i use the advantage of having a bed, and like the advantage of 4x4 and the fun-ness of having a v8. its just so hard not to floor it, or like even go the speed limit.
so your saying if i try stay under 5mph over the speed limit it'll help with my mileage a lotmore?
and what about if i put 33's or 35's and got it reageared? will my mileage stay about the same? or will it go down?

[Herbicidal]

Originally Posted by Quentin18

so your saying if i try stay under 5mph over the speed limit it'll help with my mileage a lotmore?
and what about if i put 33's or 35's and got it reageared? will my mileage stay about the same? or will it go down?

I wouldn't say a lot more, perhaps by 10% at the most. Again, with a larger tire, from my experience, your mileage would drop slightly. Now if you can always drive close to the speed limit and not floor it from time to time and drive like your granny (yeah right) and you go with larger tires and regear the mileage thing would just about even out or still be slightly less since you are running more weight with a larger tire.

Bottom line, MPG depends on so many factors, it's hard to give you an accurate estimate but again, from my experience, I can safely say your mileage will decrease, not increase.

[student's tundra]

Averaging 15mpg w/ mixed driving on my 33's and 4.30s

[Quentin18]

so i come back to my origional question. how much of a difference between mpg with 33's vs 35's?

[imjin]

Originally Posted by Quentin18

so i come back to my origional question. how much of a difference between mpg with 33's vs 35's?

I have 33's with stock gearing and I get between 12 and 14, sometimes 15 (rare) if I drive like granny and coast on the downhills. It's not a simple answer to compare to two sizes outright unless you factor in what else you've done to be able to run 35's, which usually means you've regeared to accommodate them and regearing will have a direct impact on your mpg since it affects rpm. For a 2001, we have the Tacoma 8" (210mm) rear and 7.5" (190mm) front differential, so aftermarket gearing choices are usually limited to 4.11, 4.56, 4.88, etc... There are no aftermarket 4.30 gears for the early year 1st gen Tundra, but we can use the Tacoma 4.30's which are insanely priced at the dealer so finding a used set is usually the way to go on those.

I have a set of used Tacoma 4.30 gears that I'm waiting to put in to accommodate the change in tire size, but I don't tow anything either, so 4.30's are what I'm looking for. If I did, I'd go lower with 4.56 or even 4.88 and especially if I went to a 35" tire, 4.56 or a 4.88 would be the way to go. Just going from a stock 30.6" tire to 33's while keeping stock gearing, my mpg and a noticeable but slight amount of low-end torque dropped off. What you're looking for is a good mid-range spot that balances your tire size with your gear ratio to keep it as close as possible to stock mpg performance. If you go with larger tires and don't regear, it's difficult if not impossible to keep mpg up because the motor and drivetrain are tuned to the factory tire setup, so you have to do additional things to accommodate that change and regearing is usually the way to do it. Also keep in mind that regearing will affect city versus highway mpg at certain speeds as well since you're moving the powerband in a different direction.

In my case, a 4.30 gear puts the ratio at about a 9% increase over stock gearing (3.91:1), but adding 285/75/16 (32.83" diam) tires drops it to about a 7% increase over stock which puts rpms at around 2400 running at 72mph. Stock 265/70/16 tires are 30.60", so with larger tires comes more weight and mass that the drivetrain and motor have to be able to move.

You can use the calculation below to figure up what your axle gear ratio should be close to. Falling below the New Axle Ratio value means you'll be slightly under-powered at the rear wheel and falling above the number means you'll be slightly over-powered and both directions affect mpg.

New Tire Diameter
------------------------- x Old Axle Ratio = New Axle Ratio
Old Tire Diameter

Using my numbers as an example below, stock tires were 30.60" (diam) and new tires are 32.83" and my stock gear ratio is 3.91. 32.83 divided by 30.60 = 1.07, then multipled by 3.91 comes out to 4.19. Well, you can't get a 4.19 gear and 4.11 falls slightly below what would be required, so 4.30 is the next one in line. It's a little over what I'd need, but it will give a little bit more rear wheel power than I have currently

32.83
-------- x 3.91 = 4.19
30.60

[student's tundra]

Originally Posted by imjin

I have 33's with stock gearing and I get between 12 and 14, sometimes 15 (rare) if I drive like granny and coast on the downhills. It's not a simple answer to compare to two sizes outright unless you factor in what else you've done to be able to run 35's, which usually means you've regeared to accommodate them and regearing will have a direct impact on your mpg since it affects rpm. For a 2001, we have the Tacoma 8" (210mm) rear and 7.5" (190mm) front differential, so aftermarket gearing choices are usually limited to 4.11, 4.56, 4.88, etc... There are no aftermarket 4.30 gears for the early year 1st gen Tundra, but we can use the Tacoma 4.30's which are insanely priced at the dealer so finding a used set is usually the way to go on those.

I have a set of used Tacoma 4.30 gears that I'm waiting to put in to accommodate the change in tire size, but I don't tow anything either, so 4.30's are what I'm looking for. If I did, I'd go lower with 4.56 or even 4.88 and especially if I went to a 35" tire, 4.56 or a 4.88 would be the way to go. Just going from a stock 30.6" tire to 33's while keeping stock gearing, my mpg and a noticeable but slight amount of low-end torque dropped off. What you're looking for is a good mid-range spot that balances your tire size with your gear ratio to keep it as close as possible to stock mpg performance. If you go with larger tires and don't regear, it's difficult if not impossible to keep mpg up because the motor and drivetrain are tuned to the factory tire setup, so you have to do additional things to accommodate that change and regearing is usually the way to do it. Also keep in mind that regearing will affect city versus highway mpg at certain speeds as well since you're moving the powerband in a different direction.

In my case, a 4.30 gear puts the ratio at about a 9% increase over stock gearing (3.91:1), but adding 285/75/16 (32.83" diam) tires drops it to about a 7% increase over stock which puts rpms at around 2400 running at 72mph. Stock 265/70/16 tires are 30.60", so with larger tires comes more weight and mass that the drivetrain and motor have to be able to move.

You can use the calculation below to figure up what your axle gear ratio should be close to. Falling below the New Axle Ratio value means you'll be slightly under-powered at the rear wheel and falling above the number means you'll be slightly over-powered and both directions affect mpg.

New Tire Diameter
------------------------- x Old Axle Ratio = New Axle Ratio
Old Tire Diameter

Using my numbers as an example below, stock tires were 30.60" (diam) and new tires are 32.83" and my stock gear ratio is 3.91. 32.83 divided by 30.60 = 1.07, then multipled by 3.91 comes out to 4.19. Well, you can't get a 4.19 gear and 4.11 falls slightly below what would be required, so 4.30 is the next one in line. It's a little over what I'd need, but it will give a little bit more rear wheel power than I have currently

32.83
-------- x 3.91 = 4.19
30.60

Well said, I will just add a couple of things in that not only the tacomas but also the V-6 4x4 tundras will also match up the 4.30s (as mine bought new were listed for a V-6 4x4 tundra). In addition, I will add that the Superlift Truspeed calibrator should be on your list as well unless you like doing math calculations
TruSpeed™ Speed Sensor Recalibrator · Superlift · www.superlift.com

[DavidTaylor9]

Hows this offroading? should be on tires/rims section

[imjin]

Originally Posted by DavidTaylor9

Hows this offroading? should be on tires/rims section

Why, you're right, I didn't notice that!

[editmars]

This is a good place for it, it would get lost anywhere else

[luisb6278]

Great discussion. I have a related question. I own a 2004 tundra DC 4x4 with a 6 inch RCD suspension lift. I currently have 33's and stock gears. I would like to upgrade to 35's. I tow a 5,000lb travel trailer also. what gear ratio would you all recommend, and what would I benifit by regearing? any input will be much appreciated. Thanks.