When do you switch to a 28" tall tire?

[TWISTER]

I need new drag radials and thought I had it figured out. I have 275/50/15 BFGs and want a bigger tire cause I have new wheels 15x8.5 w 3 3/8 bs and want to fill up the wheelwell more. I was goin with 255/60/15 but now leaning toward the 275/60/15. Will this hurt my 60' with a 28" tire and a 2800 convertor or worse slow my car down? I was gettin low 1.7s w BFG Drag radials. I wanted the M/T drags but I dont see the track enough to need such an aggresive performer. TIA

 

[tenright]

umm I think your getting your #'s a little mixed up here... 255 60/15 or 275 60/15 are smaller tires then your 275 50/15's actually the 275 60/15's are the same height but a smaller width. height is the first #...the higher the # the taller the tire, width is the second #, the lower the # the wider the tire. and the last # is the rim size. The largest tire I have been able to sqeeze under the car is 295-50/15's but that was with aluminum brake drums, UMI tubular uppers and lowers, Heavy duty springs, GBody custom 10" GN rims with a 3 1/2" BS, and air bags with 20 psi in them. Without notching the frame and rolling the fender lip I would say 295-50/15's is pushing the limit.


T

 

[TWISTER]

Ahh this is true as long as the tires are all of the same series such as 50 or 60 that changes width. A 275/50/15 is roughly 26" tall and 10" wide depending on maker of tire. A 255/60/15 is 27" tall and 9" wide and a 275/60/15 is 28" tall and roughly 9" wide. "I think I got that right? Maybe" But a 295/50/15 is a wider tire than I want. I just really want to filll the wheelwell up from the side as the 275/50/15 looks a little short with the front tires that are on there. Need more of the STINKBUG loook I guess lol.Thanks

 

[jasjamz]

My guess.....

275/60/15 will give you the "full look" but your 60 my get worse it may not. a taller tire is like putting in a smaller gear. Can you imagine what a TSM car would do to a 26in 10.5 tire off the line. Thats why most use 28in.

 

[jcj53115]

umm I think your getting your #'s a little mixed up here... 255 60/15 or 275 60/15 are smaller tires then your 275 50/15's actually the 275 60/15's are the same height but a smaller width. height is the first #...the higher the # the taller the tire, width is the second #, the lower the # the wider the tire. and the last # is the rim size.

T

This is mixed up as well, The first number in a metric sized tire (which almost all are today) is the tread width in mm, the second number is the height ratio to tread width and the last is the rim size. Meaning a 275/60/15 has a tread width of 275 mm/ the height is 60%of the width and it hits a 15" rim.
Just wanted to clarify this.

 

[84TXGN]

I doubt you'll lose much in the 60' time and you might gain a mph or 2 on the big end.

 

[rssooner]

I have the same question....when should you switch from a 26" tall tire to a 28" tire in regards to a performance standpoint?

thanks

 

[turbojimmy]

I have the same question....when should you switch from a 26" tall tire to a 28" tire in regards to a performance standpoint?

thanks

I've read (here I think) that 112-115 MPH is about the cross-over point for a 26 vs. 28" tire. Any faster with a 26" tire and you run out of RPM in 3rd. OD will slow you down. I switched to a 28" tire (275/60) when I hit about that MPH in the 1/4 and they're great. I can 60' better (easier to launch) and I don't have to shift into OD.

Jim

 

[TWISTER]

That was the answer I was looking for. I thought there was a mph that you had to hit to switch and I thought I was getting there,Granted I need more tuning only been the the track 2 times with the car. thanks

 

[TURBOTWIN2]

What the numbers mean...

To try and correct the misconceptions:

275/60R15, 255/60R15, 275?50R15.

The first number is a measurement in millimeters of the Section Width or fattest part of the tire at the sidewall. 275 mm=10.83 inches. This is NOT the tread width.

The next number is the measurement of the tire from bead to tread. It is a PERCENTAGE of the section width. 60 % of 275 mm = 165 mm or 6.50 inches.
50 series tire would be 50 % of 275 mm = 137.5 mm or 5.41 inches.

R = radial, 15 = rim diameter in inches.

Tread width seems to vary slightly with different manufacturers.

Real quick: 275/50R15=26" tire (stock diameter)
255/60R15=27" tire
275/60R15=28" tire
235/60R15=26" tire
The 275/50R15 is a FAT tire and wants a 8" to 10" rim. Might rub without airbags and good springs and shocks, maybe roll the fenderwell lip. I don't like these on a 7" rim.
The 255/60R15 is a good fit on a 7" rim, 8" is better.
The 275/60R15 really needs a 8" to 8 1/2" rim, but I see a lot on 7" (stock) width, which I don't like.
The 235/60R15 is great on a 7" rim and is stock diamater. 245/60R15 is OK.
Proper rim width puts the tread flat on the ground.

Hope this helps. This information is not guaranteed. Your results may vary. Don't try this at home. Closed course with professional drivers, etc.

 

[mrmixer2]

As far as tire height affecting performance, I drive a '05 International tractor for a living. It was purchased with 22.5 in rims/tires. We recently put 24.5 in. rims/tires on this vehicle and top end speed increased about 8%.
Therefore, it seems the taller the tire, the higher the top end, but most of you probably know this already.

 

[wagon]

One thing noone commented on. Your sig says 111 mph spinning. If you are spinning off the line, it will usually give you a higher mph at the top end. If you control the spinning, you probably won't hit 111. If your car is strong out of the hole, but has less power at the end, then a taller tire may help you stay in the power longer.

 

[TWISTER]

The mile per hour stayed the same but the short time was bad like a 2.0 or something that was the last time I went to the track. The track was not prepped well at all and to get a timeslip you had to go to a table and hunt for it very crappy track. I never did see a time slip just what my friends told me . I have a video of that day and you can see the car squat to the side when I left. That was after the FMIC and I just havnt madeit back. Lots of tuning to do and the only parts Im buyingis tires,Im done buying parts for awhile I have done what I want to the car and now I ready to get it dialed in hopefully. Thanks

 

[2QUIK6]

The 275/60/15 tire will fill in the wheel well nicely and give it a good look, you'll be happy with them at your power range. They make the 275/50/15 look silly small in the height dept once you see the before and after look.

 

[jlbuick]

will a 30" fit under there, 10" wide slick, how would that be over the 28.

 

[19TTA89]

NEVER.....

I run 117-118 mph on a 255-50-16 going through the traps at 5700 rpm.(15psi)

One thing that lots of people seem top overlook in this equation is the Torque Converter..If it is slipping too much,I dont care what tire you put on there,It isnt going to help.I run a ProTorque 3600 Non Lock up.

I was running 126-127 with my old car on a 255-50-16 Going into OD,That was with a Art Carr Non lock up.I have directscan files of the car going into OD at 450ft..And still running 126.

I have a friend that went from 26" to 28" tires because he was turning to much rpm...Say...5700rpm,And trapping around 114.(Locked).It didnt help at all,The converter isnt even that old,But it is not efficient.

Dont Believe that you cannot run fast on a 26" tire,Or that OD will always slow you down,Every car is different...OD certainly doesnt slow me down.If the converter is Efficient,And the the tune is there,It can be done no problem.(I have tons of Directscan files to prove it... :wink: )

 

[imjoesnuffy]

Sorry to drag up an old thread, but was just wondering.

If I can trap 123 mph on a 26" tire, any estimates on what it would do with a 28" tire? Trap rpm around 58-5900.

Just day dreaming, not gonna be at the track for a while, but just wondering.

 

[imjoesnuffy]

Sorry to drag up an old thread, but was just wondering.

If I can trap 123 mph on a 26" tire, any estimates on what it would do with a 28" tire? Trap rpm around 58-5900.

Just day dreaming, not gonna be at the track for a while, but just wondering.

Not even a guess?

 

[PaCemkr86]

275-60-15 = 28x9

 

[Mr.Spool]

twister,the 28 inch tire will require and allow you to load the car more off the line to get the car out.if you go 1.7060ft on 2psi on a 26 inch you may need 5+ to get the 1.70 on the 28.beware all 275-60-15 are not the same size,the bfg is narrower than the mickey and the hoosier is wider than both of them so measure and choose wisely.i prefer the 28 inch tire because it was much more forgiving on different tracks that are not always prepped good.as far as the need to switch from 26 to 28 i found it is truly how the car hits the tire.let the tire tell you when you need more sidewall