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Power loss going from 35" to 37" tires

14K views 22 replies 11 participants last post by  TARM 
#1 ·
What kind of power/performance loss can I expect when changing from a 35" tire to a 37" tire? I don't really tow anything so I'm only concerned about everyday normal driving, acceleration, mpg, stuff like that. I do have a dp-tuner in truck and 3.73 gears. I like the way my truck drives now and I don't want to sacrifice to much performance, so what can I expect.

Thanks
 
#2 ·
If you do not tow its not a big deal the place you will feel any loss is off the line. It is also where you will take a hit in MPG. Try taking off much easier after a stop and you will see improvement in mpg.
 
#3 ·
Might need some more information to offer advice on this one.

What's the exact size of the 35" tire you have now?

What's the exact size of the 37" tire are you thinking about running?

Are you keeping the same rims?

Installing a lift kit / leveling kit?
 
#5 ·
That's a fairly decent jump in tire size. Keep in mind its not just the overall diameter of the tire you have to consider, but the extra weight of the tire. And the extra weight of the new rims. AND you're going to be less aerodynamic (taller truck, especially if you're lifted). AND have more tire touching the ground which means more rolling resistance.

I know you have a lot of hills up there in Scranton.

My recommendation would be to re-gear, 4.10's at a minimum but its usually not worth the money to go from 3.73's to 4.10's. I think 4.30's would be a better choice.
 
#6 ·
when i geared my 7.3 i did not feel that the money spent on the gears was as justifiable as i would have hoped. i would put the $1200+ into the motor to get the performance/ mileage gains back.

fwiw i went from a 6" and 35's to a 12" and 38's and put 4.56's under it.

Did it help off the line, absolutely. Was i towing, no. If i was to go back it would have been spent on injectors and or turbo. this is if you have not already bought a trans.
 
#7 ·
......this is if you have not already bought a trans.
This is my key takeaway. The transmission.

Stock gears and big tires = higher transmission temps

Big turbo and injectors and a stock transmission = potential transmission grenade

Re-geared and big tires = transmission temps close to stock levels, acceleration close to stock performance, less risk to transmission damage



Just my $.02 and what I'd do if it was my truck.
 
#9 ·
This seems like good advice to me

we have the Yukon Gears from Randy's R&P in stock.

what kind of power are you making now, or will be making in the future?

If you EVER plan on doing injectors &/or a turbo...then I would be a little conservative on how much gear you put in there...especially if you are going to (or have) add(ed) a couple of hundred extra hp...

I ran 4.30's with 37" tires (& towed occasionally)...and when I ended up adding a couple hundred more hp...I realllllly wish I had stayed with the 3.73's/// FWIW

but everyone's towing/driving habits are different.
 
#10 ·
Remove your chip for a day and drive around. That's how your truck is going to feel w/ the 37s and w/ the chip installed. I've already been down this path. Even regeared and it wasn't as good as it had been.

Rim size is a big factor. 20" wheels also really hurt.
 
#12 ·
I love my 37's and 3.73 gears.

All Ive got is a banks(ehhh..whatever...I know what people think of this) big hoss chip that is flashed @100 hp. Which is probably more like 40 rwhp but it drives decent.

Anybody running a 4" and 35's, a 99-04, that has pics?
 
#13 ·
Don't know about 35's to 37's but I dropped 4 tenths going from the stock 285's to a 6" lift with 37's. As far as gears, they made it nicer for daily driving (I went with 4:30's) but made absolutely zero difference on the track.

.
 
#15 ·
I like that....its funny...pictures I think the 6"/37's look perfect but in real llfe they are BIG! Not cartoonishly but they stick out.

I just thought the 4" and 35's would make it look 'built' but not so attention hungry.

I just might go to the 4" and 35's...hmmmm
 
#16 ·




4" and 37's.

Wish I would have stuck with 3.73's and not regeared. Gearing is great for around town, but once on the hwy it sucks.

4.10's at most for 37's...
 
#18 ·
On the springs at full lock... The key is stock offset on the wheels. They dont hang out 5" like some guys like. There tucked in nice and tight.
 
#22 ·
I went from this...



To this within about 6 weeks (315's)... at the same time I chipped it, intake and exhaust...



I noticed a slight increase in power...LOL

From 315's to 37's I could not tell anything other then a bit more smoke taking off...



But the power kept going up the whole time too...
 
#21 ·
I noticed a big drop in power and mpg's when i went from stock to 6" lift 20" wheels and 37" tires. Then after rolling that combo for 2 years i went down to 35's and i could feel a gain in power for sure, i also gained some mpg's back.
 
#23 ·
I think split eh dif of what the extreme are here.

Go up to 4.10s and you will be fine.

On the loss of MPG 95% of with the bigger tires comes from take offs. Learn to take off super easy and slow and you will get very close if not the same MPG.


I have 4.56 to go in with my 40s from stock if its like my friends I will lose about 3 mpg and 2 if its all hwy over stock no chip etc..
 
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