Tire diameter S550

[FoMoCo]

Any advantage to running a 26” drag radial versus a 28” drag radial at the track? I have a 2019 GT with a 3.55 gear. Would it shave any et?

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[Cory S]

You definitely want a 28”. These aren’t Fox or SN95 days anymore.

 

[FoMoCo]

I understand. I was thinking for a N/A car the 26” may give me a little more gear. I have a 11.20 car, trying for that 10.90 time slip.

 

[Cory S]

MT-82 or 10R80?

 

[FoMoCo]

10R80

 

[Joshinator99]

I agree with @Cory S . If you had a stick maybe but the 10 speed gearing is probably really steep in 1st and 2nd gear already. If you have a friend with 26” drag radials maybe you could borrow them for a pass before springing for them and finding out it’s not a good fit.

 

[Cory S]

4.70 X 3.55 = 16.7:1 SLR. NOT GOOD.

 

[Jerryinpa]

Hi,

I've worked this through on my f150 tires.

For example,

I looked up 235 50 18 overall diameter which is 27.3,
If I were to change to 235 55 18 OD is 28.2

Calculate 27.3 divided by 28.2 whis is equal to 0.9680

Your speedometer will read lower with the 55 series tires. At 60 mph your dash speedometer will read 58.1 and your odometer will accumulate milage lower by the same factor.

The overall vehicle gear ratio is changed by the same factor.

Thanks, Jerry

 

[FoMoCo]

4.70 X 3.55 = 16.7:1 SLR. NOT GOOD.

What does 4.70 represent?

 

[beefcake]

a 17" wheel with a 305/45/17 street r would be your best friend at the track, if manual then the etr bias ply

let me know if we can help

 

[FoMoCo]

Thanks everyone for your input. Very much appreciated.

 

[Cory S]

What does 4.70 represent?

The 10R80 has a 1st gear ratio of 4.70:1

 

[FoMoCo]

a 17" wheel with a 305/45/17 street r would be your best friend at the track, if manual then the etr bias ply

let me know if we can help

Any negatives of running a bias ply on an automatic car at the drag strip?

 

[beefcake]

doesn't et as well typically "if" radials are working, if the radials aren't holding, then a slick / bias that is bitting and more forgiving will get you better et

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