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jonny roade
Dodge Dakota
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7/02/2003
03:19:14
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 Subject: 20 in rims perf?
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Message:
my stock 15in rims with 255/70/15 weighed 50 lbs. i got some new chrome 20s and with tires they wiegh 64 lbs. they have 255/35/20. also, i got used tires so they are kinda worn out. with my 15s, i could spin 1st,2nd and squeak 3rd, now i cant squeak at all, is this due to the balding tire or the heavier wieght? also does powerwashing damage chrome? the new rims/tires are about 1.5 inch smaller in diameter, this means that my 3.55 gear ratio prolly went up, however i wont feel a better perf. b/c of their extra wieght ( i have a 98 5.2 reg cab 5spd, also i know that the extra weight will take a toll on my brakes, so what are the biggest rotors that can be put on the front?) thanks
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Jeremy
Dodge Dakota
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7/02/2003
13:49:49
| RE: 20 in rims perf?
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Heavier unsprung weight will greater slow down your times and your ability the turn the combo over with ease when you want too. I think the rule of thumb is every lb of unsprung weight is equal to 7 hp. I'm not sure its that much, but I do know you can tell a big difference in accelerating and braking. 20's will eat stock brakes for lunch for an aggressive driver. I would not powerwash my chrome.
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Turkeyhead
Dodge Dakota
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7/02/2003
20:59:25
| RE: 20 in rims perf?
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The problem is likely the sizeable drop in overall diameter of the wheels/tires. Generally speaking, you don't want to go more than .3" (.5" MAX) larger or smaller than the stock diameter to keep the computer copasetic. Your computer is probably throwing a fit right now.
Size/Sidewall/Radius/Diameter/Circum./Revs per mi
255/70-15*7.0 in*14.5 in*29.1 in*91.3 in * 694
255/35-20*3.5 in*13.5 in*27.0 in*84.9 in * 746
7.0% difference
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jonny
Dodge Dakota
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7/03/2003
00:50:16
| RE: 20 in rims perf?
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Message:
thanks for the replies, i was under the impression that the calibration will automatically reset to the new tires, atleast thats what i read from all these post.... however i will buy new tires soon, and might get a 40 series instead of 35 if they wont rub my 3/5 drop. also 7hp per lb? so i have 14lbx4 which is 56 lbs x 7hp so i lost 300+hp? lol (at the track i saw a RT with 20s spinning and burning them up for his launch, maybe he had lightweight billet wheels or just a beefy modded motor)
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Jeremy
Dodge Dakota
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7/03/2003
13:47:46
| RE: 20 in rims perf?
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Message:
I meant 7lbs equal to 1hp loss and sprung weight is every 100lbs = 10 hp loss. sorry :)
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