Competition how much power/speed did i lose going from 265 to 315 tires....

[XcumminsX]

guys i am wondering how much power/speed i have lost from changing my tires from 265/70/17 to 315/70/17. Anyone know this?

 

[WadePatton]

try this for some info

http://www.csgnetwork.com/tireinfo4calc.html

 

[XcumminsX]

ok so if the tie circumfrence is 8. 7% bigger on my 315's does that mean my truck is 8. 7% slower than when i had my 265's... . i am very right now

 

[nickleinonen]

i don't know how much juice i lost when i went from the 265's to the 315's but i know i still have enough grunt to loose traction in 1st-5th @ ±1600rpm in wet weather. snow is even worse was in 6th today turning 1000 rpm and accelarating through some drift snow over the road and half way through it the rpm flared to about 2600 when traction went byebye [very light rear end, no ballest, WOT :-laf]



the traction situation will get better in a few weeks when my new topper shell gets in... then i can add 200-300 lbs of sand bags that won't get wet... and with the topper, i'll legally be overweight [i have my gvw registered as low as possable to avoid extra taxing and extra insurance cause i never tow/haul anything other than my arse. ]

 

[Got Smoke?]

Ask Rob Thomas.

 

[WadePatton]

Originally posted by XcumminsX

ok so if the tie circumfrence is 8. 7% bigger on my 315's does that mean my truck is 8. 7% slower than when i had my 265's... . i am very right now

Well I thought someone with racing experience might chime in. I think that is what you are asking for.



The way I see it. Your tires are 8. 7% larger, hence at any give RPM you are travelling 8. 7% faster than you were before. The speedo, if left uncorrected will be reading slower than you are actually travelling.



The performance aspect of that is you have increased the load on your engine under acceleration and, depending on your HP level, it may feel slower. If you were running out of gear--your truck felt short on legs and long on power before--then you'll probably actually BE faster. At stock HP, you may be slower, but will have a lower cruising RPM, which might help MPG.



It's just like changing the final drive gears.



More confused?

 

[XcumminsX]

YEAH! I AM A MORON

 

[WadePatton]

anything can be confusing if you think about it long enough

Give me a more specific area to work with and I'll confuse you some more.

 

[XcumminsX]

ok this is pretty much what i am worried about. 1/4 times, will the times be higher and will my run be slower because of these bigger tires? i have 4. 10 gears LSD and the rest is in my sig.

Thanks

Nick

 

[WadePatton]

Might be faster

Considering that the CR engines are pretty stout stock and you have 4. 10 gears.



Runnit and see!



Good time to have a g-tech.

 

[CumminFast]

That 4. 10 will help you out. The tires should match really well. 4. 10 isn't much of a drag racing setup. When you get 500hp the smaller tires will be alot more fun but the taller tires look better. Like I said before it feels like 100hp loss, but at 600 hp its more like 60hp. I guess what you need to do is just keep 315s and get twins. I might downsize to 33s from my 315s and see if that will be more fun on the street and not look too terrible w/ my 2" lift.

 

[XcumminsX]

so in stock form i lose power but with mods the bigger tire is better>>???

 

[WadePatton]

You're not losing any power. You're changing how the truck puts it to the ground. This can be good or bad. It really depends on how you leave the line and shift and all.



Bigger tires weigh more and put that weight further away from the axis of rotation. Those are all negatives for drag racing, because you have to accelerate that weight and the weight is "heavier" because it is further from the axis.



BUT if you were undergeared before, then you've helped the situation by letting the engine work better and not running out of gear at the top.



BOMBS help everthing!



I'm not a drag racer, nor do I play one on TV. Somebody else jump in here!

 

[XcumminsX]

so is my 4. 10 gear and 34. 5" diameter tire a good match? i plan on getting injectors (dd3) turbo (dd) bigger fuel, chip. maybe putting 475 hp to the ground is the set-up i have good for this. 4. 10-34. 5" tire dia.

 

[ECappleman]

Yes it's a good match. Running 4. 10 gears with 31" tires is definately overgeared for a diesel unless you tow a lot. Wade Patton described it well, basically in summary swapping to the 35" tires gained you an increase in maximum MPH but did cost you some in acceleration.



I think you will find that once you get the power mods done that the 35's with 4. 10 gears is about the best compromise between best acceleration and top MPH. Sure would be nice if we had twice as many RPM's to play with than what we do. I've gone the big block route and the 5000+ rpms was nice to play with but there is nothing like the low end grunt and flat torque line of a diesel. I had the BB gaser for 2 years, diesels for the last 5, I am definately a diesel person now.

 

[XcumminsX]

4x4 launches and leveling kit questions

Awesome! thanks alot guys. Hopefully i will have these mods coming soon. Gotta save the pennies and hopefully i will have a good christmas (i am 18 i still get gifts ) now what do you guys think about 4x4 launches? should i do them or no... And what do you all think of leveling kits? will this hurt my 1/4 time at all?

 

[WadePatton]

4x4 launches are pretty much the norm for drag racing... sled pulling too now that I think about it.



Leveling kit may affect your suspension/traction situation. Ladder bars would be good for getting off the line--especially in 2WD.

 

[XcumminsX]

any good ladder bars you guys would recomend for the strip? would it make my traction worse with the leveling kit? if so what else can i do to minimize it. Reason i need the leveling kit is when i turn at full lock i hear some rubbing,,,

 

[WadePatton]

Rob Thomas makes a ladder bar kit for our trucks. Look in the classifeds or do a search. It's around 600.



Leveling -raising the front- should help traction by shifting weight to the rear. It might hurt top speed and MPG by elevating your frontal area.

 

[CumminFast]

I think you might not need ladder bars unless you are planning to sled pull. I don't think the leveling kit will hurt you at the drag strip. I added a rear-add-a-leaf to pick up 2" in the back also. I think liftin the truck a bit will improve the looks of your truck tremendously. My truck sits about as high as a dodge 1500 w/ a 6" lift.