What happens if I don't re-gear?

I have 4 inch camburg spindles and an all pro 3 inch leaf pack. I want to get 33's. I understand that if I don't re-gear for bigger tires I will get bad gas milage and my truck will be slower when I press the gas from a red light, but if I do t re-gear what can happen to my truck?

Will it really wear on my transmission and/or engine??

Or will I just be slow?

Do I have to re-gear or could I just get one of those electronic chip things?

 

A chip will not substitute for gearing.

As you said, you will be slower pulling from a stop and less acceleration when you step on the gas, but you will be running a lower RPM at any given speed.
If your tranny is a manual, it will wear the clutch a bit faster if you are slipping it more to pull off from a stop as well.

 

My truck is a v6 automatic.

So no real wear and tear then?

(I mean, I'll probably, eventually, maybe get around to regearing. But it's too expensive)

 

Didn't think so

 

Oh and your speedo will be off. You will be going faster than it says on the dash, so maybe get a speedo healer or mount a GPS on the dash.

 

It'll be like those two heavy guys on the moped. vroom vroom with no zoom zoom

 

With the automatic on the highway you may find the tranny changing gears a lot between 4th and 5th gear and this can cause some premature wear on it.

 

If you are worried about it you should just get 32" tall tires. If you get a good aggressive tread they will still look great. When you have the coin do the gearing and get bigger tires down the road. Personally, i dont think you would do any damage going 33 without regear, but it could be annoying based on your driving style.

 

If RPMs are lower wouldn't that make MPGs better?

 

No bc the engine is working harder than it needs to to pull that tire...

 

After about a year running heavy 33s on stock gearing, I'm about to regear to improve power and mpgs in my mostly stop and go commute driving, and for more low end grunt on the trails.

My take is that regear is optional on 33s, and required on 35s.

 

This.

 

RPM is just a measure of how fast the engine is turning, not how hard it works to make the wheel turn (it's not a gas usage indicator). If it were, you'd expect no difference in gas mileage when towing a heavy trailer. Think of it like a bicycle wheel with your hand on the axle to turn it. If it's a smaller kid's bike wheel, it takes very little force with your hand to turn the wheel. On a larger 27" mountain bike wheel, it takes much more force to turn the wheel at the axle. However, once you're rolling, it doesn't take much to keep it going as the mass tends to keep the wheel turning.

With a larger tire, more of the mass is located further from the axle. The further the mass is from the center of the wheel, the more power it's going to take. It's not linear either. It's the square of the radius so a small increases in diameter will take much more power for each increment. So even if the wheels & tires weighed the same, it will still take more power to get the taller wheel moving.

That said, it will probably depend on how much highway driving you're doing vs city driving. With City driving, there's a lot of stop and start so you have to use much more power to get the wheel turning (and more braking power to stop it). As a result, gas mileage will drop significantly.

With a lot of highway driving, the wheel is already rolling there is not much more power used to keep it going. There will probably be a slight decrease but not that much.

I do mostly highway driving and haven't seen a significant decrease in gas mileage. Of course, mine is a manual so the gearing is different. 33s actually make my first gear more usable. My RPMs dropped about 500 at highway speeds (about 2250 at 65 mph). My understanding is the Automatics cruise at about 2000 rpm at 70mph, so think about how your truck performs acceleration wise at 1500-1700 rpm.

 

So what of I drove my truck in "3" not "D"?

P
R
N
D_4
__3
__2_L

 

Plenty of people put 33's on an automatic without regearing. I wouldn't worry about it. If you find the performance unacceptable, you can regear at a later time.