Hey, guys!

It has been quite a while since I posted on here. I was just looking at the tire and rim catalogs. I found a rim that is offered by Pro Comp under the title Series 6059 Chrome. This rim is very similar to the StoneCrusher rim except it doesn't have the StoneCrusher's cone cap. I can get them in 16x8 because they weigh about 24 pounds each. I know you guys must be wondering what I'm up to. I seriously reconsidered the 17 inchers and 265's because that involved gear swapping. I haven't gotten around to doing the gears because I spent the money on bills. So I have to put it on hold for a while. So I found the rims mentioned above and a 255/70/16LT Cooper Discoverer S/T that weighs in at 35 pounds a tire.

Now here's the question. What is the combined weight of the stock 235's and 16x7 rims I have on my truck right now? The combo I mentioned above comes in at 59-60 pounds.

If the stock combo weighs that much and the new combo weighs the same, would it allow me to not screw around with the gears and speedo?

Thanks!

 

gears/speedo has nothign to do with the weight of the wheel, it's overall diameter. the weight will slow you down and kill your mpg, but the speedo will read the same.

 

He's right.
Weight affects rotational inertia and can change the acceleration and braking characteristic of your vehcile. Even where the weight is located can make a difference.
More weight near the center of the assembly = less rotational inertia = quicker acceleration/faster braking.
More weight near the outer diameter = more rotational inertia = slower acceleration/longer braking.
Think "flywheel effect".

In general, the lower your unsprung weight (i.e. wheels, tires, brake rotors, etc.) the better off you are. But, I doubt a few pounds are going to matter that much on a 4500 lb. truck.

The rolling diameter alters your speedo/odometer readings.
larger daimeter = greater distance traveled in one revolution = speedo ain't right.

 

So what can I do to counter the slow speed and bad mileage? Those tires and rims are the lightest I could find in the catalog. Please don't mention gears because I just don't have the money right now.

What about 245's? Would that be a better alternative?

Thanks!

 

Aside from changing the rear end gear, going with a lighter/small diameter (i.e lower profile) tire would be you other option.
Remember the second number is the height of the tire as a % of the first number.
245X70-16 = 16 in inner diameter / 245 mm wide tread / .70 X 245 mm tire height.

 

So what are you saying? That I have to stay where I am now? I just want to know how big of an tire I can put on my truck without altering the gears or speedo.

I just don't like the 235's because they look too small on my truck and I want to fill up the space in the wheelwells.

I live on gravel and I don't want low profile tires because they're no good in snow and mud. I wish I had the money for gears so I wouldn't be in this situation. But I am not always lucky or rich.

Thanks!

 

for just a little size change in tires (EX: 235 to 255) I would not think a gear change would even be needed, maybe a mpg or 2 difference. I would go with the 255 tires personaly...

 

if you go from a 235/70 to say a 255/60, the overall diameter would be pretty close to the same. maybe even 255/65. i wouldnt know without doing the math.

but keep in mind 235 -> 275 is almost 1 inch wider, that's 1 inch more rubber at each corner, also meaning more traction---> more resistance---> more effort = less mpg.

and brian, the weight of my 20's makes my truck feel slow slow slow! my overall diamter grew 1 inch, but i have made no ecu changes or gear changes. one day i'll throw on 4.10's and get everything recalibrated, but for now i'm not too concerned.

to answer your question, your stock size is 235/70r16, right? that's
235/70 = 28.95
265/60 = 28.5
255/65 = 29.05
265/65 = 29.56

i think your best bet is 255/65. it wont throw off your speedo, and it'll put more meat on the road. get some nice bf goodrich a/t's which are really knobby (and actually grip like my lo-pro yokohamas) and you're set. as far as MPG is concerened, there's not much you can do here. maybe compensate with an underdrive pulley or some efans

 

4.2Manster, you got the size of my tire right. I have 235/70/16s. So I can run the 255/65/16s safely? I kinda knew I would take a MPG hit with those tires. Right now, it gets about 20 city and 22-23 highway, maybe a tad more. So if I put the 255's on, it will drop down to like 18-19 city and 20-21 mpg? Not bad for a 4x4, eh?

I can't get BFGS around here because the shop that I work at is not a BFG dealer. How light are BFGS?

Would a good filter help, along with E-fans? Are underdrive pulleys really worth the money?

When I first bought the truck, it had 255/70/16 Ameritracs. I didn't feel the difference between them and the 235s currently on my truck. My boss made me drop down 2 sizes to keep the speedo reading correctly. When I wear out the 235's, I will definitely put the 255's on along with a fancy set of rims.

I really appreciate all of the replies from you guys. You have helped me out greatly!

Thanks!!

 

BOF,
FWIW, my 2000 came with 255 tires. I went with 265's last time (got a good deal on them). I didn't notice any change in anything. Acceleration, braking, mpg...no real difference.
According to my GPS, the speedo is dead on. Maybe it was a little off with the 255's ?
My truck has the 3.55 rear end. What do you have?
If you have 3.55 gear, then I'd think the 255's would be fine.

 

There's got to be some tolerance, well, bad choice of words....

A small change, say 1", will not throw it off too drastically...it's all math really.

As for the BFG's, they are heavy. Heavy as heck! Common/inexpensive tires, if you want a knobby off-road look, Dunlop, Bridgestone, hell even General makes A/T's..They will always be heavier than your standard tire...but they look so cool! The BFG's are just a good all around tire, and I've installed them, they are HEAVY!!! heavy enough to scratch up your arm or shoulder when the tread rubs against you =(

With my 20's, i get about 15mpg avg. That's a reg. cab, 5spd 2wd. Before the 20's, i got about 16mpg. With the MPG you're getting, i'd say anything is worth a shot!!!

The pulley's have been said to help quite a bit, but some say they have had problems with it slowing everything else down (belt-driven). Everyone I know with them have no problems. Along with the pulleys, e-fans are supposed to have great bottom-end gains, and I noticed a good power increase throughout the entire RPM-band with my MAC intake.

 

BrianA, I have 3.55 gears. Did your truck originally come with 255's? My original size was 235/70/16 but I bought the truck with 255's. I didn't feel any difference, but my boss made me drop down to OEM size. I'm glad to know I can put 255's back on without difficulty.

BTW, how is your '05 F150 treating you? Have you done anything to it lately?

4.2Manster, are they really that heavy? I changed tires on a Expedition and it had BFGS at all 4 corners and we threw two of them away. They felt light. Maybe because they're worn out?

I prefer Cooper because they're made in America and they are relatively cheap. They have a weight penalty. But they have that aggressive off road stance that I'm after.

Have you seen a Cooper Discoverer S/T? Cooper rates them as a mud and snow tire with very good manners on the highway. They look real aggressive and I'll definitely put them on my truck.

About my MPG, you know I have a regular cab long box 4x4 and a 5 speed. I always keep it at 70 with cruise on. That's how I get those figures. Why is there such a BIG difference in mileage? Is it dependent on how you drive it, where you live and so on?

Thanks for the tips on the mods. I will do that as soon as I get paid again. Having bills to pay ABSOLUTELY sucks! Sorry for the long reply!

Thanks again!