Nicelysedate

iTrader: (3)

Hello!

Currently I am running 275/40/17 street tires at the track on my stalled auto Trans AM. I starting to go fast enough were I am hitting 4th going through the traps @ around 114. My car has a 3600 stall and 4.11's with a 4l60e.

I was thinking of going to a 28" tire to give me more room. Or maybe a 27" tire.

Thoughts? Opinions?

MidwestChassis2

iTrader: (1)

What distance away from the traps are you shifting into fourth or are you shifting right at the trap? If right at the trap or close enough have you tried to push it past your shift point to see if the vehicle possibly picks up or if you are to far out and can't turn enough RPM then that will decide what tire height to go with to gain the extra distance you need.

Nicelysedate

iTrader: (3)

I am 6400 rpm when it shifts @ 114 and my trap speed is 114.5 with a DA of 1000 ft with it starting to get cooler it just gonna get faster. Stock bottom end on pac 1218 Springs so I don't want to push my rpm much higher.

Blackbirdws6

iTrader: (7)

If you plan on keeping the car as is, a 27 would probably be a good choice so you can run out 3rd going through the traps. If you are adding significant power soon, a 28 may be better. Play with the rpm/speed calculators to figure out a bit to confirm.

MidwestChassis2

iTrader: (1)

Blackbirdws6 nailed it on the head. Some of the online calculators can be extremely helpful.