help needed on tyre size change verse 1/4 mile runs

[maca]

Hey guys
I have been running 245x60x14 tyres which help me at the 1/4 mile cross the line in top gear at full rpm so its just right at the moment. The big problem is I cant stick it off the mark and through 1st gear. It is 430rwhp and just spins the wheels. I have found a nice set of 275/60/15 rims and tyres which are semi slicks.
Using a tyre calculator it says they are 2.42 inches taller than what I am using now. As I will also be chasing more HP eventually so taller tyres might be fine.
Anyone have any idea or some sort of calculator I can use to compare the two tire sizes down the quarter or tell me what to expect as I haven't got much tyre experience.
cheers maca

 

[71DodgeDemon340]

Have you looked at running a us size drag tire? Such as mickey thompson.
Not anything other than a 26x8.50-14 available in a 14 but if you go to a 26x10.00-15 then theoretically you will be able to keep it in the same rpm at the end of the quarter, being a bias tire and wider, should allow you the desired grip on the launch, lower tire pressure will also assist you

http://m.summitracing.com/parts/mtt-3053


Heres another good option.
26x10.5-15 MT sportsman
http://m.summitracing.com/parts/mtt-6542

Or if you want to run a radial go with a 275/50r15 nitto nt 555

A 275/50r15 is right at the same height as a 245/60r14.
The 275 will put you at the same height and allow for wider tire footprint to gain traction

Heres the specs on your size vs the 275/50r15

Tire Size - 245/60R14

Section Width:

9.65 in

245.00 mm

Rim Diameter:

14 in

355.6 mm

Rim Width Range:

7 - 8.5 in

Overall Diameter:

25.57 in

649.60 mm

Sidewall Height:

5.79 in

147.00 mm

Radius:

12.79 in

324.80 mm

Circumference:

80.35 in

2,040.78 mm

Revs per Mile:

813.30/mi

Actual Speed:

62.14 mph

100.00 kph

Speed Variance:

-

Diameter Variance:


Tire Size 1 - 275/50R15

Section Width:

10.83 in

275.00 mm

Rim Diameter:

15 in

381 mm

Rim Width Range:

7.5 - 9.5 in

Overall Diameter:

25.83 in

656.00 mm

Sidewall Height:

5.41 in

137.50 mm

Radius:

12.91 in

328.00 mm

Circumference:

81.14 in

2,060.88 mm

Revs per Mile:

805.37/mi

Actual Speed:

62.75 mph

100.99 kph

Speed Variance:

0.98% too slow.

Diameter Variance:

0.99%

 

[maca]

Thanks for your response
I have looked for a 14" drag tyre but couldn't find one. I will check out summit. The 26x8.50 14 you mentioned, is the 8.5 the width in inches? If it is what width rim will I need as I can measure to see if it will fit my rim now as it currently has 245x60x14 on it but did have a wider tyre on it before
The other tyres I have found near me are mickey tompson ETs and come with rims which means I can save on rims. They are 275x60x15
I am upping my boost from 8 to 12 psi so I was thinking the extra hp might let me have a 15" tyre but I have no idea what extra hp I might get and how the 15" tyres will run with this set up.
Maybe I need to do the extra boost 1st before tyres

 

[71DodgeDemon340]

The 8.50 is in inches bit will be close to the same width as the 245, however going from a street radial to a drag tire in the same width will improve traction noticably.

Recommended wheel width on the 26x8.5-14 is 7-9 inches.

What are you running up front?

May be worth while to go to the 26x10-15 or a 275/50r15 drag radial
Both these sizes are almost identical to your 245/60r14 height (within 1/4" overall) however they are wider which will increase your rolling resistance slightly. you need the width to hook. The time youll gain from not spinning at launch will be more than the one hundreth or one thousanth of a second lost at the end due to rolling resistance. Also the bias ply drag tires will weigh less than the radials.