Yeah, its another late night and i'm bored. on that note...



I keep seeing threads for higher hp cars about "what slicks should i run" "what size slicks should i get" and people just spitting out answers. Well here's your answer and why. M&H 24.5x8.5x15, or M&H 23x8.5x15.

M&H 23"
M&H 24.5"

Now you may say "23"s!?!?". Yes, 23"s... and here's why.

F35 Gearing:
1st-3.38
2nd-1.76
3rd-1.18
4th-.89
5th.7
LSJ 4.05 / LNF 3.82

With that being said for the sake of this article i'll use a 235/40/18 tire and a 7,200rpm rev limit for my "stock data" as thats what majority of this community runs for a tire and limit.


With that tire and limit, RPM vs Gear looks like this (for sake of space i'll only be showing 6200-7200)

LSJ 4.05

RPM 1st 2nd 3rd 4th 5th
6200 34 66 98 130 165
6300 35 67 100 132 168
6400 35 68 101 134 171
6500 36 69 103 136 173
6600 36 70 104 138 176
6700 37 71 106 140 179
6800 38 72 108 143 181
6900 38 73 109 145 184
7000 39 74 111 147 187
7100 39 75 112 149 189
7200 40 76 114 151 192


LNF 3.82

RPM 1st 2nd 3rd 4th 5th
6200 36 70 104 138 175
6300 37 71 106 140 178
6400 37 72 107 142 181
6500 38 73 109 144 184
6600 39 74 111 147 187
6700 39 75 112 149 189
6800 40 76 114 151 192
6900 40 78 116 153 195
7000 41 79 117 156 198
7100 42 80 119 158 201
7200 42 81 121 160 203

So based on that, LNF's are alright but higher hp LSJ's are right in a bad spot when it comes to crossing the line in 3rd vs 4th. But no one likes to race on a street tire and that low of a rev limit. so lets say that they're running a drag radial. 245/50/16 Nitto NT555R and an 8,100 limit. Now i know you're saying "who the hell runs an 8,100 limit!?" well a lot of us do actually, and its quite helpful. Buuut because some of you don't.... i'll go ahead and show from 7200-8100

LSJ 4.05

RPM 1st 2nd 3rd 4th 5th
7200 40 77 115 153 194
7300 41 78 117 155 197
7400 41 79 118 157 200
7500 42 80 120 159 202
7600 42 82 122 161 205
7700 43 83 123 163 208
7800 44 84 125 165 210
7900 44 85 126 168 213
8000 45 86 128 170 216
8100 45 87 130 172 218


LNF 3.82

RPM 1st 2nd 3rd 4th 5th
7200 43 82 122 162 206
7300 43 83 124 164 209
7400 44 84 126 166 212
7500 44 85 127 169 214
7600 45 86 129 171 217
7700 46 88 131 173 220
7800 46 89 132 175 223
7900 47 90 134 178 226
8000 47 91 136 180 229
8100 48 92 137 182 232

Now thats better. See why we like the upped rev limit?? 130mph 3rd for an LSJ and 137mph 3rd for an LNF. But now you're getting in to numbers so high that means theres going to be a lot of lag on the low end. Even at 7500rpms thats still 120 for an LSJ and 127 for an LNF. But lets face it if you're serious about drag racing and want to lay down some times, you're going to be running a slick. And thats why i wrote this, and this is how you get rid of that low end lag. By switching to a slick not only will you hook up better and put the power down, (for this forget about the whole "oh yeah don't chya know, dropping your 60' a tenth will lower your ET by two!"), you will actually accelerate faster. And here's why.

Changing the diameter of your tire to be shorter or taller will increase or decrease your rate of acceleration respectively. Its like in your physics class when you make the small gear turn the big gear, it barely turns. But when you make the big gear turn the small gear it makes it wind the hell out. So "mathematically" speaking, when you switch to a smaller tire, it has the same affect as if you were to keep the tire you had and switched to a shorter, or higher number, gear. Let me explain it in numbers..

From the lists above..(brought out to 8,100 for comparison)

LSJ 4.05
RPM 1st 2nd 3rd 4th 5th
235/40/18 street tire 8100 45 86 128 170 216
Nitto NT555r drag radial 8100 45 87 130 172 218
M&H 23" drag slick 8100 41 79 117 156 198


LNF 3.82
RPM 1st 2nd 3rd 4th 5th
235/40/18 street tire 8100 45 86 128 170 216
Nitto NT555r drag radial 8100 45 87 130 172 218
M&H 23" drag slick 8100 43 84 125 165 210

Take a look at the MPH's now that they're all together. First of all forget about street tire's they just don't hook up and aren't worth it. Lets compare the slicks vs the Nittos. LSJ's have plenty of room to shift to 4th and keep on truckin. LNF's however are a bit iffy, but the reason i'm going to say it's okay is because if you're on an engine revving to 8100, and trapping close to 125mph and still on the factory 3.82, its probably about done So with the numbers above we see the lsj will power through and keep on truckin' into 4th. LNFs should be good to trap in 3rd. With these slicks 60' and 330' times will drop like pants on prom night. 60' marker is only 720" from the stage beam. With the 23" slicks roll out of 73" that means in less than 10 revolutions of the tire you're already past the 60' mark and on to the 330' mark. If you take a look at the MPH's listed above. you see that for each car, 1st ends at low 40mph. And lets be honest we've all done a 40roll and know how they feel. So when you shift into 2nd it will still pull hard as hell. Even harder because of the smaller tire. Let me explain that a bit more in depth..

The reason for the mph drop is because going to a small tire is like changing gears without opening up the transmission. Its why a small tire will allow you to accelerate faster and why too tall of a tire kills acceleration.

here's the nittos/gear/rpm vs mph for the lsj

1st-3.38-8100rpm@45mph
2nd-1.76-8100rpm@87mph
3rd-1.18-8100rpm@130mph.

Because the 23.3" is 2.4" shorter than the 25.7" nitto. The car will accelerate as if you were running a shorter gear. But you aren't you're just on a smaller tire. So if you wanted to keep the nittos and accelerate like you were on the M&Hs you'd need to change the gears to the following in order for the gears to end at the same MPH.

1st-3.73
2nd-1.94
3rd-1.3

And thats what makes the gear end sooner, or "shorter" compared to running the nitto.


If you've been paying attention, you noticed i mention two slicks at the beginning and have only been talking about one. Thats because in my opinion, factoring in the factory final drives for the LNF and LSJ, and track times people have pulled on these 23"s. I feel its more than enough to get the job done on a factory final drive. Now for those of you who already have the 4.45 trans you already know that you should be running a 24.5. Switching to a 4.45 and running a 24.5 you're gearing will look like this..

LNF/LSJ 4.45

RPM 1st 2nd 3rd 4th 5th
7500 36 70 104 138 175
7600 37 71 105 140 178
7700 37 72 107 142 180
7800 38 73 108 144 183
7900 38 74 110 145 185
8000 39 74 111 147 187
8100 39 75 112 149 190

Which basically could not get any better. perfect balance of powerband, acceleration, and tire. So there you have it, don't say i never helped you guys. Now if only i could help myself....


For those that think 24.5" isn't enough tire....

 

Somebody buy this man a set of 15x8 racing steelies!

 

lol

 

lol
Now break all this down for the 4t45e and the L61 JK

 

nice write up man lol

 

 

you know how bored i get at night. hahah

 

makes picture about other transmissions. didn't go look at the drag times thread.

 

i will likely never drag my car

 

lmao

 

what the **** did i just try to read

 

Yes, I understand fully now. XD

 

sticky for sure

 

I am now dumber after attempting to read that for the fact that I tried to actually turn my brain on in which it failed

 

You guys have got to be kidding... All he did was explain extremely simplistic information on a silver platter.

Now.. What are the options rim-wise for a Brembo LNF if one wants to keep them?

 

ahh ****..
he's back again.

 

You can also look at it in terms of power. If you have a lsj or lnf on stock turbo and make in the 300 hp range I would run a 23 inch slick to like you said improve the gear ratio and acceleration. Higher hp and I would run a 24.5. Wouldnt go any higher than that.

 

wheel wise? couldn't tell ya. never owned an lnf or test fit anything. from what ive read though it seems as if basically any 17 will fit with a small spacer to clear the outer face of the calipers. iirc its not the top of the caliper that hits, just the face of it.

 

chris would you mind posting some pictures in here of your 15"s and 24.5's so people can see that it still is quite a bit of tire.

 

Nice write up. Im going to a lsj trans so this is some good info.

 

i now have a chronic migraine thanks to sexcocker1921!

but wow very good info, i've been thinking before if it would be better to run taller or shorter tires... its like with shorter tires its quicker but lower top, and with big tires it might be too hard to lug all that rotational mass around but top ends better...

with another readthrough or two i might understand this much better good write man.

 

well if you get bored again you should do one for the f23 I need to get my times down cuz 13.3 @ 118 on 205/55r15 drag radials is kinda lame lol

 

26"x9.5" I hate these heavy wheels and size. Better than street tires, though.

 

Here is the brakes and were they need to be ground down. And a pick of the car sitting on the slicks.

 

Hey, I know that mod!