01FbTaWs6

iTrader: (12)

Hey guys, I am swapping to a Th350 here this weekend from a T56. My question is what size tire do I need to run? it is a street car and will see highway time and interstate time, quite often really. I drive it to and from the track, no trailer. The car is a full bolt on, 226/230 cam/cnc ported ls6 heads milled to 58cc, full rear suspension car, S60 with 4.10 gear. made 425/395 on the dyno through T56 with 4.10's. The trans will have a FTI 4400 stall converter, and a brake. I was thinking a 28 tall tire would still net me very good short times, and be better for street driving. A buddy disagrees. He thinks a 26 tall would be alot better. im interested to hear your guys beliefs.

69_YENKO

iTrader: (16)

I had a TH350 and 4.10's and 295/50/15s (about 26" tall) in a previous project and it was sitting at 3000rpm at 55mph, was fun at the track but not really good on the highway.

heres where you will be sitting with a 26" tire
Engine Speed (RPM) Speed (MPH)
8000 RPM 150.93 MPH
7500 RPM 141.49 MPH
7000 RPM 132.06 MPH
6500 RPM 122.63 MPH
6000 RPM 113.20 MPH
5500 RPM 103.76 MPH
5000 RPM 94.33 MPH
4500 RPM 84.90 MPH
4000 RPM 75.46 MPH
3500 RPM 66.03 MPH
3000 RPM 56.60 MPH
2500 RPM 47.16 MPH
2000 RPM 37.73 MPH
1500 RPM 28.30 MPH
1000 RPM 18.87 MPH

heres a 28" tire

Engine Speed (RPM) Speed (MPH)
8000 RPM 162.54 MPH
7500 RPM 152.38 MPH
7000 RPM 142.22 MPH
6500 RPM 132.06 MPH
6000 RPM 121.90 MPH
5500 RPM 111.74 MPH
5000 RPM 101.59 MPH
4500 RPM 91.43 MPH
4000 RPM 81.27 MPH
3500 RPM 71.11 MPH
3000 RPM 60.95 MPH
2500 RPM 50.79 MPH
2000 RPM 40.63 MPH
1500 RPM 30.48 MPH
1000 RPM 20.32 MPH

01FbTaWs6

iTrader: (12)

the above is not taking into account converter slippage is it??

69_YENKO

iTrader: (16)

no, its just a rough guide based off the final gear ratios and tire size, you'll actually get a little less MPH then listed for each RPM point

Dave J

iTrader: (2)

I have 410 gears and I go through the traps at 7000 rpm right at around 128 mph
prolly not so good on the freeway

TJ

iTrader: (10)

youll benefit from the 28" for street cruising, and depending on how the motor or car likes it, you may be more consistant at the track with the larger sidewall.

BAIN

iTrader: (5)

I have been the 4.10 28" ET Drag route at around the same power levels as you. With the higher first gear of the TH350 matched with 28" tall slick you will loose some 60' and they will grow down the track about 1-1.5" and kill some ET & MPH also.

I just switched to 26" ET Drags to see if I can make up some 60' (if I can get them to hook) and hopefully ET & MPH better.

Oh and BTW even with the 28" tire the 4.10's will put you way up in the rpm range at HWY speeds like stated above.