4.30 Gears

[semperfidoordie]

So I pulled the window sticker and my truck has 4.30 gears...wondering what size tires would bring the RPMs down to around a 3.73 gear ratio...or around that. I'm thinking 315s but wasn't sure what was acceptable on stock 17s and what all I'd need. I'd assume a leveling kit but don't know for sure

[Ryan Rønning]

My tires are about the equivalent of 32's and I run around 2300 rpm at 70 or 75. I am not sure how big you would have to get to a reasonable RPM.

[H0USE]

315 is the width of a tire, you need to increase the middle number of the tire measurement, eventually you just get into inches like 33 or 35, just remember if you increase your tire height dont go too wide otherwise you will have more resistance, so keep them tall and skinny for lower rpms to get better mpg.

[Buffalo444]

Originally Posted by semperfidoordie

So I pulled the window sticker and my truck has 4.30 gears...wondering what size tires would bring the RPMs down to around a 3.73 gear ratio...or around that. I'm thinking 315s but wasn't sure what was acceptable on stock 17s and what all I'd need. I'd assume a leveling kit but don't know for sure

What is your stock tire size? with this infomation we can give you a better answer

[Buffalo444]

Never mind, did it for you!

37 inch outside diameter tires would put you at about the same operational range as 3.73's on 32's.

However, something you have to remember when going to a tire that large is A) you ad a bigger profile to both the truck and the tire, because you will have to lift it, and the tires will be wider and B) you add a lot of unsprung weight to the truck. Any form of compensation performance wise will just be pulled back by those two.

[semperfidoordie]

True...just wondering what would be a better mileage gain bigger tires or a gear swap to 3.73s or deleting the DPF/cat and running a good exhaust....just really don't like have to go 58-60 to keep the RPMs around 2k

[semperfidoordie]

Figured I would update this....my first tank since deleting...about 3/8 tank was still dpf on with the tuner the rest was fully deleted on the Hot Damn tune...saw 13.75 mpg overall...not terrible compared to 12 to 12.5 bone stock. Hoping my next tank fully deleted will yield a little better results but well see. The speed was kept between 60 and 65 with a few times where I got on it to feel the nice new power

[semperfidoordie]

Wanted to throw another question out there...has anyone with 4.30 gears gone to a taller tire? If so has anyone seen an increase in mileage? I figured with the torque of a diesel the weight shouldn't bother it at all but the increased height seems like you'd turn lower RPMs on the freeway.

[Robelyn100]

My dually has the 4:30 gears as well. Mileage sucks so run 11.5 - 13.5 unloaded and 7.5 - 11 towing a 35' fifth wheel RV. Been toying with changing gears to 4:10 or 3:73. what's involved & typical expense.

[Boreal]

I've been wondering that myself. My 450 is geared really low (I think 4.88s?), so I'm considering a re-gear myself. In the Jeep world it's typically ~$500 per axle, which would include new gears, master rebuild kit, and labor. I would suspect this truck to be about the same....