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27" Tyre Help or Hinder

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WesternRed View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote WesternRed Quote  Post ReplyReply Direct Link To This Post Topic: 27" Tyre Help or Hinder
    Posted: Feb/25/2014 at 12:37am
Have the chance to pick up some 255/60/15 (27") drag radials for a good price, I'm currently running 265/50/14 (24.4") BF Goodrich Radial T/As that are probably 20 years old. 60' times are pretty crap at the moment, around 2.2-2.4 seconds and it spins off the line if you load it up so presumably more traction would help. The only problem is that I currently have 2.87 rear gears so the 27" tyre is going the wrong way in terms of gearing so I don't know if I will go forwards or backwards with these tyres.
 
Have some 3.5 gears planned for down the track, which would probably help with the larger tires or just forget the tires and change the gears?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote spottydog360 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/25/2014 at 5:03am
20 year old tyres is the answer,we have 18 year old Eager 265 50 14s on the back of Lisas 68,Im ok to drive around on them but don't expect them to stick to anything,they will be as hard as heck.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote spottydog360 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/25/2014 at 5:05am
Sorry answer should be taller tyres acceleration deficiency should be offset by better grip.Unless the new tyres are also 20 years old.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote FuzzFace2 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/25/2014 at 11:08pm
Originally posted by spottydog360 spottydog360 wrote:

Sorry answer should be taller tyres acceleration deficiency should be offset by better grip.Unless the new tyres are also 20 years old.

Not with that 2.87 gear.
With the shorter tire and that they spin off the line helps get the motor up in RPM/power band.
Say you have the same short tire you have now but does not spin off the line again with that gear it will pull the RPM down below the power curve and be a dog.
Now add a taller tire & does not spin it will be even worst.
 
My 75 Gremlin stock 304/auto w/2.87 gear and street 14" tires I would try and get the tires to spin a little off the line to get the motor up in RPM faster. Thru the lights (1320) I could do it in 2nd gear or 3rd and get the same time as it would go into 3rd almost at the line.
Thats me story and I am sticking to it Wink
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75 Gremlin X v8 for sale
70 Javelin 360/auto drag car
70 Javelin 360/T5 Street car
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Post Options Post Options   Thanks (0) Thanks(0)   Quote WesternRed Quote  Post ReplyReply Direct Link To This Post Posted: Feb/26/2014 at 12:03am
Yes, I can hold second over the line as well or change up just before with the 2.87 gears.
 
I'm thinking the 27" tire may be a bit too tall even with the 3.45 gears, most other tyre options would put me around 25.5"-26.0". I need to get away from the 14" wheels because there really isn't much out there in the way of tires for them these days, particularly if you are chasing a bit of traction.
 
Basically looking to get from a high 13 to a low 13 or maybe even dip into the 12's if I can manage it. I should have enough power to get there, has run just over 102 mph, mainly need to get out of the hole a bit quicker.


Edited by WesternRed - Feb/26/2014 at 12:06am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote spottydog360 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/26/2014 at 2:17am
Yeah I can see that,I have no experience in this.Other than street burnouts
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Post Options Post Options   Thanks (0) Thanks(0)   Quote FuzzFace2 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/26/2014 at 6:50am
In my Drag car (70 Javelin) 4.56 gear and 28" tire is turning a little over 6k at the line and the converter slip is with in spec. 13-13.5 sec little over 100mph IIRC
For my combo a 4.10 gear would be good but 4.56 is all I have for now.
Play with the numbers at the below sites may help
I would say 27" tire with better traction with 3.73 gear might be the ticket.
Dave ----
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75 Gremlin X v8 for sale
70 Javelin 360/auto drag car
70 Javelin 360/T5 Street car
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WesternRed View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote WesternRed Quote  Post ReplyReply Direct Link To This Post Posted: Feb/27/2014 at 10:40pm
Looks like I will be testing this out, will have to give it at least one run with the 2.87 gears to see what happens. Does anybody want to lay bets on faster or slower?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote WesternRed Quote  Post ReplyReply Direct Link To This Post Posted: Feb/28/2014 at 6:12am

Before:

After:

 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote 390spirit Quote  Post ReplyReply Direct Link To This Post Posted: Feb/28/2014 at 8:19am
you won't have any traction problems with the M/T ET Street tires, if you do then its time to look at the rear suspension....springs, shocks and pinion angle to make sure they are good and set right

I had the rear out of my car last year and when I put it back in I tightened the 4 link bars just a little too much and it wouldn't let the suspension work the way its intended to...at the track all it would do is spin all the way threw 2nd gear, 2.0's for 60' times, I came home and loosened all the mounting bolts, let the car set on the ground and then just tighten till the lock nuts touched, next weekend it was putting down 1.52 60foot times

just food for thought
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