Intake and exhaust gains enough to offset larger tires?

[Tdotsfinest]

Just had a levelling kit installed on my truck today. Currently running BFG KO2 275/55R20 (stock size) but going up to 275/60R20 once these tires are worn. Just wondering if the HP and torque gains from an intake and cat-back exhaust would offset the loss caused by larger diameter tires?  My truck has the 5.3, 6 speed with 3.42 gears.

[michigan2500hd]

Just had a levelling kit installed on my truck today. Currently running BFG KO2 275/55R20 (stock size) but going up to 275/60R20 once these tires are worn. Just wondering if the HP and torque gains from an intake and cat-back exhaust would offset the loss caused by larger diameter tires?  My truck has the 5.3, 6 speed with 3.42 gears.

You're basically going from a 3.42 gear to a 3.31 with that size tire. I doubt you're going to make up for the "off the line acceleration" feeling with a intake and/ or a exhaust. I've have both on many trucks and going back to smaller tires at times always made a big difference. A tune would help the most. The exhausts on these trucks flow decent and usually give the best feeling of torque off the line. The intakes flow plenty for a stock engine.

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[Rob Okray]

Before I ditched the stock muffler, flapper, and resonator in favor of a Flowmaster, I could get a chirp and a maybe a short squeal out of the tires. Now I can get a legit burn out and the truck actually scoots a bit to the left before TC kicks in. What that means in gains, is anyones guess, but I like it.

[Tdotsfinest]

Thanks for the input guys!  Sounds like I may have to swap gears for 3.73s if I don’t like how the truck pulls my trailer with the bigger tires. 

[.justin.]

If you're already unhappy with it while towing, it will only get worse with the heavier tires.  In our experience, the exhaust system and right intake will certainly help, but won't completely overcome the difference made by the new tires.  Tuning can help improve response and drivability all around, but especially so regarding shift patterns to work with the heavier components.  A few extra MPH on a shift point can make worlds of difference in your case.

[Tdotsfinest]

1 hour ago, .justin. said:

If you're already unhappy with it while towing, it will only get worse with the heavier tires.  In our experience, the exhaust system and right intake will certainly help, but won't completely overcome the difference made by the new tires.  Tuning can help improve response and drivability all around, but especially so regarding shift patterns to work with the heavier components.  A few extra MPH on a shift point can make worlds of difference in your case.

I’m quite happy with the truck’s towing characteristics now, it pulls my 7x16 ATC enclosed cargo trailer with no issues. I just don’t want the truck to have to work too hard when the trailer is fully loaded, at around 6000-6500 lbs

[.justin.]

2 minutes ago, Tdotsfinest said:

I’m quite happy with the truck’s towing characteristics now, it pulls my 7x16 ATC enclosed cargo trailer with no issues. I just don’t want the truck to have to work too hard when the trailer is fully loaded, at around 6000-6500 lbs

My apologies, I mis-read your post before.  "IF" is a big operative word.  

[Tdotsfinest]

26 minutes ago, .justin. said:

My apologies, I mis-read your post before.  "IF" is a big operative word.  

No worries at all!  I’m going to be putting an intake and exhaust on regardless, leaning towards the Borla touring series and not too sure which intake I’ll be going with yet. I’m kind of thinking that I should swap the tires before an intake and exhaust to make an actual comparison in towing performance. 

[SkiDooNick700]

My two cents is the exhaust and intake aren't going to make enough power at your regular driving RPM range to offset the bigger tires when cruising on the highway.  When pullin up a hill turning out 4,000+ RPM, then the HP from those kicks in and yes I could then see it help with offsetting the larger tires.

 

Either way, I would still get the bit bigger tire as well :-)  

[Tdotsfinest]

32 minutes ago, SkiDooNick700 said:

My two cents is the exhaust and intake aren't going to make enough power at your regular driving RPM range to offset the bigger tires when cruising on the highway.  When pullin up a hill turning out 4,000+ RPM, then the HP from those kicks in and yes I could then see it help with offsetting the larger tires.

 

Either way, I would still get the bit bigger tire as well :-)  

I agree, I doubt there will be much difference when pulling along flat stretches. I’m really hoping that the gains are enough to break even on hills like you said and when passing. I did a gear swap on my ‘05 Sierra 1500 to pull a 26’ (32’ overall) ATC enclosed car hauler but I’d prefer to not have to swap gears in this truck.  I’ll be doing 700 km drives to and from work in the GTA twice/week once we move up north, in addition to driving to work during the week. I have to tread carefully because I have to keep fuel economy in mind when I’m not pulling the trailer. 

[Grumpy Bear]

Someone mentioned early on that this tire swap represents an effective gear change of 3%. He gave it in ratio but....it's a math problem. For the suggested modifications to 'offset' the ratio change in absolute wheel torque the question becomes; does this modification give a 3% across the entire rpm range boost in torque? Your 'effective' towing range would be from converter stall to peak horsepower rpm.