what 15" tire for the track?

[roadrunner-r]

205x50x15 or 205x55x15 or225x50x15?

[NovaResource]

None of them are good. Alll of those are too short.Your best choice is a 205/60-15.Others choices are: 215/60-15 or 225/55-15.

[roadrunner-r]

I thought that was the whole point. So you can stay in lift like the celica. Haven't you seen the video's. He stays in lift at 6500rpm every shift. I think thats on of the the mods that is helping the that Matrix run a 14.6 I PM'ed him but no answer.

[NovaResource]

Changing the tire height and or final drive ratio won't change the rpm drop between shifts. Yes, shorter tires will help you accelerate slightly quicker similar to installing a lower (numerically higher) final gear ratio however, engine rpm drop between gear is still the same. You have to change the gear ratios in the transmission to do that.

[roadrunner-r]

i was looking at the 205x55x15 = 23.6 Stock 215x50x17=25.5 Its 1.9" shoter than stock. Stock final drive is 4.56... With the smaller tire it should put me at 550+ easy. Thats a good soild 2+ tenths and maybe a 1mph higher trap. Dont you think? I have a O2 trans am ws6 and i know when you do a gear change that big. It will drop your 1/4 times If iam correct this is a worth while mod for the track. Iam going with the Pepboys futrua Z tires and their cheapy rim's. My friend works their and he said that he would hook me up. ONly chargeing me for one tire and one rim. it comes out to 155 with taxes. 2 tenths for 155 ,thats cheaper then the intake. I know i should get drags but if i lanch at 4k its dont spin maybe just a chripI just need some feedback from some that has done this before no offense. The only ones that i know of is the two guys from Perico. That to my knoladge are that fastest N/A Matrix in the world.

[NovaResource]

You have a couple of errors. First, a 205/55-15 tire has a 23.9" diameter, not 23.6". That means they are only 1.6" shorter, not 1.9" shorter. Second, the final gear ratio is 4.53, not 4.56. Third, changing from a 25.5" tire to a 23.9" tire gives an effective gear ratio change from 4.53 to 4.83, not 5.50+. This change is very minimal. Lastly, using smaller tires will LOWER your trap speed, not raise it. You will get a couple hundreths, maybe 1 tenth at best but that's about it.

[roadrunner-r]

Well ill just go with a 205x50x15 That makes it 23.1,and how do you know> If i go with a 255x55x15 my gear ratios will change to 480 from 453!??

[NovaResource]

quote:how do you know> If i go with a 255x55x15 my gear ratios will change to 480 from 453!??Simple:A 23.9" diameter tire has a circumference of 75.1" (23.9 x 3.14159)A 25.5" diameter tire has a circumference of 80.1" (25.5 x 3.14159)Divide 75.1 by 80.1 and you get .937Divide 4.53 by .937 and you get 4.83To get an effective gear ratio of 5.50, you would need a 21" tall tire.4.53 / 5.50 = .823680.1" x .8236 = 65.97" circumference65.97 / 3.14159 = 20.999" diameter tire[note] 3.14159 is the constant PI

[drunkenmaxx]

oh my god! i have a headache.

[roadrunner-r]

I figures it out with a 205x50x15 =23.1 that will put me at a final gear ratio of 5.01I dont know how much that is gonna help. BUt with the lighter wheels and tires setup and the gear ratio change. I say 1.5 tenths now for 155 thats a dam good price. What do you think??

[goodvibe]

It wont lower your trap because it will be easier to pull RPM with the lower final. It should actually go up. As long as you don't drop the final enough to cause an additional shift to 4th and lose that shift time, it should be great. Doesn't help lift a bit.

[roadrunner-r]

(Goodvibe) Thats what i was thinking to,but who knows until i try it or someone else does.