i dont want to change out the stock wheels on my 6 when i got to a 4.10. i love the stock look and dont want to change a single thing. but i am worried that installing 4.10s on the stock GYRFs will be a near fruitless endeavor. i am scoping the PS2's, at least for the rear tires, in maybe a 295 or 305 width on the stock rim. will the 305 bulge too much? i dont want to lose any lateral performance, and so if the 305 sidewall will rollover on the stock rim, then i dont want to go to that size.

has anyone else tried to solve the traction problem of having the stock runflates mated with 4.10s? how did you do it?

 

I would try the GYRF's first. You might be surprised with the traction. I had a mid year vette with low gears, 4.11, then 4.56 and then 3.08 when it was sold. The low gears had much better traction than the high gears. Once the high gears break loose, they never want to stop spinning.

 

if yoru going with a 4.10 you want a much sticker tire. Mich PS and GYRF wont grab like they way you want.

4.10s will give you much better acceleration but also limit top end.

 

i though the PS2s were some of the stickiest street tires out there. and certainly, light years stickier than the factory GYRFs. i dont have a Z51, so i dont have the supercar RFs. i dont want drag radials and i dont want to spend $5-6k on bigger rims and tires. like i said...i like the stock rims just fine.

 

I have 4.10's and ps2's... Before the supercharger the car had 406rwhp the 4.10's+ps2's were GREAT... with 620rwhp on tap now, they are worthless in a rollon until 4th gear... I'll be changing back to 3.42's soon...
Jeremy

 

Not true sir. I had 4.10's. Sixth gear becomes a usable gear. I did 180 in sixth gear at 4700 rpm (C5) and it was still climbing as it is the low end of the power band.

If you mean on a track in 4th gear then it is true. Assuming you had a H/C job done you gain some top gear rpm from raising the rev limiter to 6800-7000 like I did. My cars are not drag cars.

I beleive you will still have the ability to get to 130 in the 1/4 with them. I sure someone knows the exact number @ 6800 or so. However if you use gyrf I assume we are taking about street use since I would buy a drink for anyone who hit that trap speed with the runflats...hehe. If you are using the car on the track then instead of 3.90's you can use a 28" tall tire to get the top speed back.

 

awesome! are you running the PS2s in the stock sizes, or did you go a few MM wider on the back?

620rwhp YO!!!!!

 

The only PS2's made in a 295 or wider are "30" series tires. These are a smaller OD than stock. That effectively lowers your gearing even more. You'd have to run the numbers, but I'd guess it would take you to about 4.20 effective gearing. If you are going to do that, you might want to reconsider a 3.90 gear.

 

excellent point! you definitely have earned "mod advisor of the year award" J. thanks!

back to the drawing board for now...

 

I agree with SpinMonster relative to the impact of 4.10's and the power in sixth gear. I have a 2006 with 4.10's installed by Cartek and the power in sixth gear is great. At 165 MPH the car is pulling hard, but that's my limit. I'd like to know the top speed a 2006 is capable of in sixth gear with 4.10's. Maybe a math genius can do some calculations for us.

 

Not true...Mine are 25 series 295x25x20 and measure within 3mm of stock diameter, that is the measurement taken by me... Not calculated...
Jeremy

 

These small differences in gearing are not noticable. As any tuner will tell you as I wa told, going from 3.42 to 3.73 is hardly noticable so going from 4.10's to a smaller diameter tire will hardly be too.

FWIW, a guy in the C5 section that runs the BFG kdw2 295/35 which is 27" tall hooks well with them and has gotten 1.77 60' times. I know from owning them that they do in fact outhandle the stock Z51 supercar tires. I have seen repeated 1.03G's on the HUD.....275 up front/295 rear.

 

maybe he meant for the 19's, since i am just trying to re-wrap the stock rims.

 

Most guys who road race never use 4.10s, normally 3.42s or 3.73s. and a 6900 max red line. GM testing LSx engines are safe to 6900 rpms.

28" ? I have 28 1/2" diameter x18x12 Good Year G19s in my basment. Tires are so darn sticky they almost ooze rubber just sitting there. ANyone want them?? $25 each plus $25 shipping / tire. one heat cycle
I have 4 tires. They would be $400 each if new.

Oppps Sorry got side tracked when talking abotu gears and sticky tires.

 

I think this is the way to look at 4.10s: they basically move each gear up a full ratio. That is - second now behaves like 1st, 3rd is basically like second used to be, except with an extra 10 mph in it etc. Accordingly, the car will now make it's top speed in sixth, and that speed will be very close to what it achieved in 5th before the gear swap.

For this reason, I do not think one can generalize about 4.10s being "bad" for road racing. On a tight course where one was in 2nd a lot, moving the 40-80mph range into 3rd gear and having an extra 10 mph to play with is quite nice - same punch with extra legs. You could wind up actually shifting less than you did before. In other cases, the "add one gear + 15%" may not work. You have to think about where you run the car and whether it works for you. That said, you still have to deal with the car's weakness: the 4-5 hole. And, no gear set is optimal for all tracks. That's why us Formula Mazda guys run around with 3-4 different gear sets.

Which brings us to the new 1st gear. For guys like me, who granny launch with no clutch drop and who are stock-motored, the extra punch is welcome although it is unlikely the tires will hold. I don;t care since I'm getting Nitto R2's anyway. It is also good for drag racers on stickies, obviously. And it would avoid the whole skip-shift nonsense, which on this car is really bad (since you just go from 2nd now in most cases). It will also give the Z51 cars the same thrust as the new Z06, to 60, if that's important (of course you lose 0.5 sec for the shift 0-60, but you had to shift anyway).

But I would say it is no good for modded engines or for guys who actually know how to launch on the street.

 

Sorry, When I posted that,I was referring to 19" diameter tires as I had not researched the 20's.

I just looked at Michelins spec sheet on PS2s. They show the 295/25-19 as being just over an inch smaller in OD than the 285/35-19! That is a lot.

 

It is a lot and that wheel well needs filling.

 

You just saved Mayonayze a lot of money. If the difference between a 4.10 and a 3.90 is hardly noticable, then why not go with a 3.90? Of course, the difference between a 3.90 and a 3.73 will hardly be noticable, so why not go with a 3.73. Ooops! What was I thinking? The difference between a 3.73 and a 3.42 will hardly be noticable, so he can just stick with the stock 3.42!

Sorry - couldn't resist. All in fun

 

danged progressive logic!!!!