37" Bfg,Methods,Mid perch

[RaptorFlipper]

So some clarification on the mpg. I have had the 37's for about 8 month's and my average mpg has dropped .2 over the entire course of the vehicles history(close to 30k in miles). So more accurately it is probably .3, .4 mpg. I don't give a shit about mileage like couple of you guys said, and I didn't buy this truck to worry about fuel economy. I drive pretty hard, so I do not think the mpg was affected that much. Lekrap is right there is a slight loss in acceleration, but I am talking slight. BUT, I have every bolt on/tune/air enhancement possible on my truck. 565 hp at the rear wheel, so an NA raptor, or less modified one might see a bigger decrease in the acceleration. Wouldn't know, did all the engine mods first, then the tires.

 

[Bulletnjm]

So some clarification on the mpg. I have had the 37's for about 8 month's and my average mpg has dropped .2 over the entire course of the vehicles history(close to 30k in miles). So more accurately it is probably .3, .4 mpg. I don't give a shit about mileage like couple of you guys said, and I didn't buy this truck to worry about fuel economy. I drive pretty hard, so I do not think the mpg was affected that much. Lekrap is right there is a slight loss in acceleration, but I am talking slight. BUT, I have every bolt on/tune/air enhancement possible on my truck. 565 hp at the rear wheel, so an NA raptor, or less modified one might see a bigger decrease in the acceleration. Wouldn't know, did all the engine mods first, then the tires.

Putting 565 hp to the wheels is certainly incredible for a stock drivetrain. I am curious to see how well the stock drivetrain will hold up. I assume you must drive it hard all the time? Do you have anything for the transmission?

 

[RaptorFlipper]

Good point Bullet! I do drive fairly hard all the time. I am going to upgrade the driveshaft next month. You can see skylar's thread on here where she snapped her drivetrain when she jumped on her sc raptor a few years a go. My tech is super knowledgable and really only works on race cars and my truck, so I am just doing what he says. No problems so far. What were thinking on the transmission? Upgraded billet pump? I have thought about changing the gears, but it is expensive, and really how much faster can or do I need to go?

 

[LekRap]

Thanks @RaptorFlipper for the further explaining the MPG's and acceleration. I definitely wasn't trying to be a **** or "call anyone out" or anything like that. Just was trying to clarify some things that I had heard about 37's from friends. I also had 37's very quickly on my truck (had an old set that I slapped on some extra wheels). I didn't recalibrate the computer for the adjusted rev's per mile, so my onboard computer was way off. The consensus from guys I've talked to about it was about a loss of 2 MPG's from 37's (even lighter 37's like BFG all terrains). That would make sense to me since the truck has to work harder on acceleration to spin a larger diameter tire.

I've always been very impressed with how well the raptors handle stock 35ish sized tires. I personally feel like 37's push it over the edge slightly (on a relatively stock/ NA motor). But I will have to admit that 37's look bad ass on raptors. I think the supercharger makes that basically a non issue to you RaptorFlipper. Guess it's just a personal preference thing. I still go back and forth, but I actually still have time to think as I am only about 1/2 way through my stock 315's.

 

[RaptorFlipper]

Wow! I can tell you it is not 2 mpg loss. At least not for me. That is a lot. Strange how people get different mpg's everywhere. Anyway, the 37's really look good, but I would assume with no sc, you would see a drop in acceleration for sure. I just like how they fill out the well more. And bfg's are not true 37's either. More like 36's really. I think the exact measurement is around 36.2. Otherwise there would be rubbing for sure.

 

[CAraptor]

Yes

---------- Post added at 06:16 PM ---------- Previous post was at 06:12 PM ----------

I have whippel super charger and 37s but I drive it hard and get 8.5 mpg. I was getting 10 before 37 and supercharger but accelerating much slower. Lol

 

[BAJA1K]

FYI Bfg 37x12.5x17 AT weighs 71.3 lbs. General grabber 35x12.5x17 weigh 77 lbs. So just because some tires are 37" does not mean they are heavier.

 

[LekRap]

FYI Bfg 37x12.5x17 AT weighs 71.3 lbs. General grabber 35x12.5x17 weigh 77 lbs. So just because some tires are 37" does not mean they are heavier.

I realize that weight is a big factor, but isn't overall circumference also a contributing factor? No matter what the weight, the truck still have to spin a larger diameter tire. That has to take more effort, right?

 

[BAJA1K]

I realize that weight is a big factor, but isn't overall circumference also a contributing factor? No matter what the weight, the truck still have to spin a larger diameter tire. That has to take more effort, right?

My opinion is that if the weight is lighter the only possible issue is the tire clearing the fenders and turning radius. I do not think it takes any more effort to spin a lighter tire just because its bigger. I think someone with physics knowledge can tell us.

---------- Post added at 08:49 PM ---------- Previous post was at 08:31 PM ----------

My opinion is that if the weight is lighter the only possible issue is the tire clearing the fenders and turning radius. I do not think it takes any more effort to spin a lighter tire just because its bigger. I think someone with physics knowledge can tell us.

Looks like there is thread already called unsprung weight vs. rotating mass. Very interesting write up.

 

[Truckzor]

My opinion is that if the weight is lighter the only possible issue is the tire clearing the fenders and turning radius. I do not think it takes any more effort to spin a lighter tire just because its bigger. I think someone with physics knowledge can tell us.

Swapping to larger diameter tires is the same thing as swapping to a higher gear ratio, which requires more power to move the truck, as the engine has less leverage.