tire size vs. gear
tire size vs. gear Just wondering if yall think my ET will increase any or stay the same. Last season i was running a 26" tire(255/50/16) with a 3:23 gear. The fastest i ever ran with it was a 11.59 with a 1.60 60ft. Next season I am switching to a 28" tire(275/60/15) and a 3:73 gear. With all other things being the same do you all think my times will increase much or do you think the gears will just kind of balance out having a taller tire? Also if it makes much of a difference im only running a vig3200 stall. Whenever i get my transmission rebuilt I will end up switching to a bigger one, but that wont be till this tranny dies.
thanks,
Brandon
thanks,
Brandon
A 28" tire will slow you down alot if your not putting down some horse power. Most guys that run the 28" tire are cutting 1.4 or faster 60fts.
I would run a 255/50/15 DR's with the 3.73 gears,that will net you a better over all ET with your gear and converter. I used to have that converter years ago and it works really well. My buddy has it now and has ran several 1.59 60fts. NA and a few high 1.4 60fts. on the bottle with the tire i stated above with a 3.23-3.73 gears.
Sell those 28" and get the 26" tall tire or you will regret having them.
I would run a 255/50/15 DR's with the 3.73 gears,that will net you a better over all ET with your gear and converter. I used to have that converter years ago and it works really well. My buddy has it now and has ran several 1.59 60fts. NA and a few high 1.4 60fts. on the bottle with the tire i stated above with a 3.23-3.73 gears.
Sell those 28" and get the 26" tall tire or you will regret having them.
whats your mph right now? you might still be able to get away with a 26", if not a 27". how high do you want to rev? whats your suspension setup? are you going to use a nitrous controller or you coming out on the full shot? Based on these questions you might need the 28's just to hook rather than get you through the traps
i think i may try to spray out of the hole. Right now my MPH is around 115 through the traps(i think i am spinning a very little). For suspension im still on stock shocks and springs which is killing it, but i do have a PHB, TQ arm, and LCAs. Im thinking the times on motor might stay around the same since im going to a 28" tire, but also going from the 3:23 gear to a 3:73 gear.
basic rule of thumb is that two inches of tire is equal to about one gear set.
so going from a 26" tire with 3.23's to a 28" tall tire with 3.73's would be the gearing equivalent of just switching to 3.42 gears. not really a change that is worth anything.
if you are looking to optimize your gears for track performance you kind of have to start at the finish line and work your way backwards. you want your gearing and tire size to work together to produce a trap RPM that is a bit past the peak power rpm as you cross the line. so if you make peak power at 6k rpm you want to cross the line at 6200-6400 rpm to make sure you use every last drop of power as you go down the lane.
so going from a 26" tire with 3.23's to a 28" tall tire with 3.73's would be the gearing equivalent of just switching to 3.42 gears. not really a change that is worth anything.
if you are looking to optimize your gears for track performance you kind of have to start at the finish line and work your way backwards. you want your gearing and tire size to work together to produce a trap RPM that is a bit past the peak power rpm as you cross the line. so if you make peak power at 6k rpm you want to cross the line at 6200-6400 rpm to make sure you use every last drop of power as you go down the lane.
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Hmmm. On your best, pass, a 1.60 right, did you spin? You need to know going forward so that you can figure out if you have more in it NA. A low 1.5 would you get in high 11.4's potentially. Your NA MPH would go up if you ran more gear (and still with 26's).
I'm spraying 150 off the transbrake on 28" slicks, went 1.38.
I'm spraying 150 off the transbrake on 28" slicks, went 1.38.
On a car we run it runs a 31" tire and 5.13 and went 9.30 with a 1.30 60ft.
You could do it with a shorter tire but the taller tire sure helps when you start adding more power to it, especially leaving with nitrous right off the go.
Bigger tires will slow you down, but having a little more tire really helps keep it consistent and when the track you run at isn't it's best it really helps.
On a car with a marginal chassis set up or adjustability the bigger tire can really help the 60ft.
You could do it with a shorter tire but the taller tire sure helps when you start adding more power to it, especially leaving with nitrous right off the go.
Bigger tires will slow you down, but having a little more tire really helps keep it consistent and when the track you run at isn't it's best it really helps.
On a car with a marginal chassis set up or adjustability the bigger tire can really help the 60ft.
Just raise your rev limiter. I cut 1.42 60's N/A M6,4.11's on a 26'' tire. I can spray a 150 shot out of the hole and still make it down the track around 6,800-rpm's on the 26'' tires. you should only need an extra 300 to 400 rpm raise on the rev.
my rev limiter is at 6600 i believe, and im going to leave it there. I dont wanna push the stock rod bolts. I guess ill just have to wait and see how i do next season.
I can tell you this. I have an 02 SS convertible with the 3.23 gears and the stock 275's on 17" rims. I put on 28"X11.50"X15" rims. Basically a 325-50-15 ET Streets. Before I hooked up the HP Tuner, the speedo was 2mph off from the new setting. The difference is when you add power such as 150HP of N20, the smaller rim/bigger tire combo will absorb so much more shock than the big rim/small sidewall combo. This combo will work on the street with a mild motor and after some mods to the suspension. I have the BMR Extreme suspension in the rear with a Dana 60 w/4.10's, Strange adjustable shocks, Strange chrome moly shaft w/1350 joints. This spring I will get the adjustable fronts and BMR front kit. I'm running the car at full weight, over 4100lbs, I'm 267 of it. The bad thing about a convertible is weight and weight distribution. I'm looking for a 00-02 hardtop to start fresh. In the mean time everything that bolts on can unbolt. With the NX150HP setting on the stock bottom end, I got this Leviathon down the track with a 1.5-60'. 7.0@102mph. in the eight. 11.0@126 in the 1/4. It has ET Performance stage 2 heads and about a .600" Comp Cam. After 3 years of having fun I finally spun a bearing the last pass of the last race of the night. It will now have a 382" with a Callies 4" stroke crank and 6.125" rods. Diamond pistons with their coatings. Now the block will be the only thing to hold me back.
A 3.73 gear and 28" tall will shorten your gear some, so it may help your NA time some, but probably not noticible
To be honest what I would do first is change the gear and keep the SAME tire for now. You can still trap 135 at 6500rpm with a 26" tall tire and 3.73 gear, so that should be more than enough for your N2O mph. If you still have a 10 bolt the lower your gear the more likely they are to break. A 3.23 will be stronger just due to size...
Here is a good website you can play with gear ratios and tire sizes all day long....
http://www.f-body.org/gears/
Chris
To be honest what I would do first is change the gear and keep the SAME tire for now. You can still trap 135 at 6500rpm with a 26" tall tire and 3.73 gear, so that should be more than enough for your N2O mph. If you still have a 10 bolt the lower your gear the more likely they are to break. A 3.23 will be stronger just due to size...
Here is a good website you can play with gear ratios and tire sizes all day long....
http://www.f-body.org/gears/
Chris
A 3.73 gear and 28" tall will shorten your gear some, so it may help your NA time some, but probably not noticible
To be honest what I would do first is change the gear and keep the SAME tire for now. You can still trap 135 at 6500rpm with a 26" tall tire and 3.73 gear, so that should be more than enough for your N2O mph. If you still have a 10 bolt the lower your gear the more likely they are to break. A 3.23 will be stronger just due to size...
Here is a good website you can play with gear ratios and tire sizes all day long....
http://www.f-body.org/gears/
Chris
To be honest what I would do first is change the gear and keep the SAME tire for now. You can still trap 135 at 6500rpm with a 26" tall tire and 3.73 gear, so that should be more than enough for your N2O mph. If you still have a 10 bolt the lower your gear the more likely they are to break. A 3.23 will be stronger just due to size...
Here is a good website you can play with gear ratios and tire sizes all day long....
http://www.f-body.org/gears/
Chris
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Joined: Aug 2005
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From: Tampa, FL
Brandon,
With a 26" tire and a 1:1 tranny ratio here is your mph vs rpm:
Speed (RPM)...Speed (MPH)
8000 RPM 191.58 MPH
7500 RPM 179.61 MPH
7000 RPM 167.63 MPH
6500 RPM 155.66 MPH
6000 RPM 143.68 MPH
5500 RPM 131.71 MPH
5000 RPM 119.74 MPH
4500 RPM 107.76 MPH
And here is 3.73's with a 28" tire:
Speed (RPM)..Speed (MPH)
8000 RPM 178.66 MPH
7500 RPM 167.49 MPH
7000 RPM 156.33 MPH
6500 RPM 145.16 MPH
6000 RPM 133.99 MPH
5500 RPM 122.83 MPH
5000 RPM 111.66 MPH
4500 RPM 100.50 MPH
So by going with 3.73's and 28" tires you will numerically increase your overal gear ratio and it should increase acceleration and decrease top end. -Mark
With a 26" tire and a 1:1 tranny ratio here is your mph vs rpm:
Speed (RPM)...Speed (MPH)
8000 RPM 191.58 MPH
7500 RPM 179.61 MPH
7000 RPM 167.63 MPH
6500 RPM 155.66 MPH
6000 RPM 143.68 MPH
5500 RPM 131.71 MPH
5000 RPM 119.74 MPH
4500 RPM 107.76 MPH
And here is 3.73's with a 28" tire:
Speed (RPM)..Speed (MPH)
8000 RPM 178.66 MPH
7500 RPM 167.49 MPH
7000 RPM 156.33 MPH
6500 RPM 145.16 MPH
6000 RPM 133.99 MPH
5500 RPM 122.83 MPH
5000 RPM 111.66 MPH
4500 RPM 100.50 MPH
So by going with 3.73's and 28" tires you will numerically increase your overal gear ratio and it should increase acceleration and decrease top end. -Mark