Performance Effect With 35" Tires?
Post Fiend
Joined: Jul 2005
Posts: 14,582
Likes: 12
From: 21791
Don't forget the extra weight and rolling resistance also runs up your EGT's. Switching from a tire/wheel combo that weighs 73lbs (stock/305) to 125lbs (20's and 35's), the EGTs go up considerably, almost 150-200* higher when pulling a hill in OD. Unloaded, just driving around in 80e, i can roll in to the throttle at 1350 or so RPM and watch the EGT steadily climb as high as i want, the hill is usually over at 1250*.
FTE Leadership Emeritus
Joined: Sep 2003
Posts: 12,258
Likes: 771
From: Houston, Texas
For a 7.3, 4r100 combo 4.30 gears are overkill for the 315/75/16s. I thought they would've helped with rolling resistance and everything else taken into consideration; but it made things worse. How? At 65 my engine was turning about 2200 rpms instead of the usual 1900. My truck didn't work as hard as it did to take off or maintain speed, but it really drank down diesel in the process overall. To top if off, I spoke with two reputable FTE sponsors independently and they both said that I had over compensated for my tires; and unless I planned for 37s, I should go to 4.10. With the 4.10 setup I've got now, my truck is back to the way it used to be minus .5 to 1 mpg; but I'm sure that's nothing a DP Tuner chip won't fix. 
Not a liberal...
Joined: Jul 2006
Posts: 6,635
Likes: 4
From: Cut & Shoot, Texas
Don't forget the extra weight and rolling resistance also runs up your EGT's. Switching from a tire/wheel combo that weighs 73lbs (stock/305) to 125lbs (20's and 35's), the EGTs go up considerably, almost 150-200* higher when pulling a hill in OD. Unloaded, just driving around in 80e, i can roll in to the throttle at 1350 or so RPM and watch the EGT steadily climb as high as i want, the hill is usually over at 1250*.
Post Fiend
Joined: Jun 2004
Posts: 9,293
Likes: 10
From: Parker, CO
That's why I had to do a gear swap on my truck. The high altitude makes it even worse. Unloaded I could barely make it up a mountain pass in O/D in the 40 tow with the 36" tires and 3.73 gears. Swapping to the 4.30's helped keep those temps in check by bringing the RPM's up to the proper range.
Junior User
Joined: Jun 2007
Posts: 82
Likes: 0
From: Eldorado springs,Mo
I have cooper 315 A/Ts. In 80E i can roast them at will. I also have 3.73s. My best hwy mileage was 21.68mpg unloaded going from Vegas to Cali running with the cruise set on 70mph
. I did it with my DP in 80E
Country
. I did it with my DP in 80ECountry
FTE Leadership Emeritus
Joined: Sep 2003
Posts: 12,258
Likes: 771
From: Houston, Texas
I don't know what it was, but my truck just hated the 3.73s even with my SCT. Around town it got no more than 12 or 13 and it would work getting off the line. (I could roast tires, but still) On the freeway I very seldom saw more than 15-16 mpg (barely got 17 once); it would climb hills and the turbo would surge and surge climbing at 65 or 70. Now with the 4.10s, it just quietly whistles and my truck climbs without a problem or any surging.
The DP-Tuner may have alot to do with it, but did you have any other tuner before DP?
Junior User
Joined: Jun 2007
Posts: 82
Likes: 0
From: Eldorado springs,Mo
Not bad mileage at all.
I don't know what it was, but my truck just hated the 3.73s even with my SCT. Around town it got no more than 12 or 13 and it would work getting off the line. (I could roast tires, but still) On the freeway I very seldom saw more than 15-16 mpg (barely got 17 once); it would climb hills and the turbo would surge and surge climbing at 65 or 70. Now with the 4.10s, it just quietly whistles and my truck climbs without a problem or any surging.
The DP-Tuner may have alot to do with it, but did you have any other tuner before DP?
I don't know what it was, but my truck just hated the 3.73s even with my SCT. Around town it got no more than 12 or 13 and it would work getting off the line. (I could roast tires, but still) On the freeway I very seldom saw more than 15-16 mpg (barely got 17 once); it would climb hills and the turbo would surge and surge climbing at 65 or 70. Now with the 4.10s, it just quietly whistles and my truck climbs without a problem or any surging.
The DP-Tuner may have alot to do with it, but did you have any other tuner before DP?
Music to my ears. Around vegas i get on average 14.5-16. Did the 4.10s help out a lot ? I was kicking around the idea.Country
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FTE Leadership Emeritus
Joined: Sep 2003
Posts: 12,258
Likes: 771
From: Houston, Texas
Yes I had a few... The first Superchips tuner for our 7.3's, Superchips FlashPaq( Nice for a off the shelf tuner).I had a problem with surging until i put in my Wicked Wheel. Now all I hear is LOUD wistle and NO surge. Boy how i love the whistle Music to my ears. Around vegas i get on average 14.5-16. Did the 4.10s help out a lot ? I was kicking around the idea.
Country
Music to my ears. Around vegas i get on average 14.5-16. Did the 4.10s help out a lot ? I was kicking around the idea.Country
I do however think that my truck needs to be tuned for the tires and 4.10 gears as I suspect that the canned SCT tunes are meant for a 3.73 truck. Hence the DP-Tuner chip...How do you like the 80E and 120 race?
What do they do for you power and mileage wise?
I was thinking of going with NS, S, 80T, 80E, 100, and 120 race.
Lead Driver
Joined: May 2007
Posts: 5,613
Likes: 9
From: Flagstaff, Arizona
It put the truck back in it's power band and got my speedo within 5 mph of where it should be. I.e. 60 is 65 at 1900rpms, 50 is 55 at 1600rpms, and so on as if my truck had the stock tires on. My engine and tranny thanked me by giving me back my mileage and power to spare. I do however think that my truck needs to be tuned for the tires and 4.10 gears as I suspect that the canned SCT tunes are meant for a 3.73 truck. Hence the DP-Tuner chip...
How do you like the 80E and 120 race?
What do they do for you power and mileage wise?
I was thinking of going with NS, S, 80T, 80E, 100, and 120 race.
I do however think that my truck needs to be tuned for the tires and 4.10 gears as I suspect that the canned SCT tunes are meant for a 3.73 truck. Hence the DP-Tuner chip...How do you like the 80E and 120 race?
What do they do for you power and mileage wise?
I was thinking of going with NS, S, 80T, 80E, 100, and 120 race.
FTE Leadership Emeritus
Joined: Sep 2003
Posts: 12,258
Likes: 771
From: Houston, Texas
Lead Driver
Joined: May 2007
Posts: 5,613
Likes: 9
From: Flagstaff, Arizona
Senior User
Joined: May 2006
Posts: 482
Likes: 0
From: Woodside, CA
I love it, im running a stock 02 7.3(awaiting Jody's return) and i can bbq my 38 Mickey MTZ's like they're nothing. I did it twice without even thinking about it and thats with stock gears. if you guys are serious about not being able to burn your tires you have got a really light foot. and for bottom end grunt, it might not all be there but i can still feel it.
Junior User
Joined: Mar 2008
Posts: 89
Likes: 0
From: Dallas/Fort Worth
i know this is kinda 
but im curious what kinda MPS's y'all are getting with the bigger tires and how y'all calculate it. Im running 35 M/Ts and getting like 13mpg empty truck, not towing nothing about 50/50 city/highway.
23 gallons gave me 300miles roughly
Paul,
but im curious what kinda MPS's y'all are getting with the bigger tires and how y'all calculate it. Im running 35 M/Ts and getting like 13mpg empty truck, not towing nothing about 50/50 city/highway. 23 gallons gave me 300miles roughly
Paul,
Post Fiend
Joined: Jul 2005
Posts: 14,582
Likes: 12
From: 21791
For the chip, take it from me. I have a chip with NS, S, hi idle, 40t, 60t, 80hybrid t/e, 120r, 140a and smoke lope. Im getting my chip reburnt like this: NS, S, Hi idle, 60, 80, 140 all with 60t's transmission tuning. I find myself driving around on the weaker 60t just because i like how the transmission shifts. It's a noticeable shift with nice lockup strategies, however on the 80 and above there's just a noticeable slip by having the TC unlocked in a gear too high for my liking, and when it shifts you can't feel it.