Is it worth stepping up to a 28" tall tire?

[mike93lx]

This winter, I am hoping to get new gears in my 8.8 and I can't decide on tire size. If i stick with a 26" tall tire (most likey 275/50 15 M/T dr's) I will go with a 4.10 rear gear. If I go 28" (most likely 275/60/15 M/T dr's) I will go with a 4.30 rear gear. The problem comes with cost...4.10's are $40 cheaper and the tires are about $20 more for the pair. I know its not a ton, but will the 28's hook that much better than the 26's and will I run into problems going 2.3" taller than stock?

She will stay n/a for the time being...I'm getting a bike before a blower.

If someone can show me a stock ride height notch with 28" rear tires, I bet the look alone will convince me to go for the 28's.

Thanks

 

[shorty1993]

what are your plans for the car? and if i might ask why stay with the 15" rims. if you want looks and performance go with a 17" wheel and 245/45/17 DRs and drop it a little. you get looks, traction, and some performance from the suspension change. that is just my opinion. someone else will surely come up with something more educated.

 

[TIMMY2734]

ummm he wants to hook.....why on earth would he want a 17" rim?

What are you gonna rev the car too? Id probably stay with the 4.10s if a blower is in the near future. That may even be too much unless you plan oin spinning the thing. After you decide on the gears, the tire can be worked out. Maybe borrow a set from a friend and givem a whirl.......

 

[Michael Yount]

If you get the right bike, you won't care about the blower.

If traction is what you're after, I'd make the tire decision based on that -- and then change other things to make the tires work. By the way, you'll loose a little effective gear with the options you're considering. The combination of the 28/4.30 is a little "taller" in effective gear ratio than the 26/4.10 combo. Said another way - if you're trapping with a little too much rpm with the 4.10/26 combo, the 4.30/28 combo will give you a few more rpm to work with.

 

[Pops Fun]

Hi,
I have 28" tires on the back, 325/50/15 bfg dr's, they hook pretty good. Turned up the wheel lip,took off quad shocks and beat in the wheel wells.
I have 3.73 gears and go through the trap at about 6200 in 3rd. They look great on the car. Make sure your fronts and rears are close to the same size or your abs will give you a light and won't work, like mine ..
I am looking at either 4:10's or a supercharger to fix my problem with the trap rpm.
Question will the supercharger do it?? Engine gets to rpm faster and I will have to shift to 4th??

Edit:

Steve

 

[mike93lx]

shorty1993 - looks are important, but it seems we prefer a different style. i had the car dropped, and hated it. 17's aren't gonna hook nearly as well, and personally, 28x11.50 et streets on draglites will look pretty sweet.

timmy - blower isn't happening for a while. if i do end up getting the blower, i'll change the rear gears again. i'd like to be able to rev it into the upper end of 6000rpm

michael - i know what you mean about the bike. a buddy of mine has an early 90's zx600r (just low 12's) and it feels faster than my mustang.
i've gone through all the math (when i'm bored at work, i'll sit and do gear calculations, pathetic huh? ) and I have a spreadsheet to map it all out.
the difference is very slight. at the stock limiter (6250), 4th will give 121mph with the 4.30/28" combo vs. 117 with the 4.10/26" combo.

steve - thanks for the pic. unfortunately i doubt i'll stuff 325's in the wheelwells of my notch, but the height looks awesome. and although i wish i had to worry about abs, fox's don't have it, so i can throw some stock height tires up front and get a little rake.

thanks!

 

[Michael Yount]

Steve - your car would be MUCH quicker if you got it geared with those tires so that you're going through the traps at peak rpm in 4th, not 3rd. You need a set of 4.30's, maybe even 4.56's.

 

[Pops Fun]

Steve - your car would be MUCH quicker if you got it geared with those tires so that you're going through the traps at peak rpm in 4th, not 3rd. You need a set of 4.30's, maybe even 4.56's.

Hi,
Mike93lx.. sorry to steal the thread, but

Michael, I am I wrong to think a supercharger will increase speed/rpm and move when/where I shift into 4th, or do I need gears too??

Steve

 

[Michael Yount]

Steve - I made an assumption about your tranny type. What kind of tranny are you running?

If it's a manual, most guys trying to optimize 1/4 mile times would want to use the torque multiplication of the first 4 gears -- that means gearing/tire size so you cross the line at the or near the power peak in 4th gear, not third. Your taller tires make your 3.73's act like less gear. With that tall a tire - 4.10's or 4.30's would allow you to get well into 4th before the end of the track. What rpm did your torque and power peaks occur at?

 

[Pops Fun]

Steve - I made an assumption about your tranny type. What kind of tranny are you running?

If it's a manual, most guys trying to optimize 1/4 mile times would want to use the torque multiplication of the first 4 gears -- that means gearing/tire size so you cross the line at the or near the power peak in 4th gear, not third. Your taller tires make your 3.73's act like less gear. With that tall a tire - 4.10's or 4.30's would allow you to get well into 4th before the end of the track. What rpm did your torque and power peaks occur at?

Hi,
Manual transmission.
Here are attached files tmoss figured for me in thread
http://forums.stangnet.com/showthread.php?t=476861

Hope this helps, I understand that the taller tires change my effective gear ratio. just not sure what do do about it??

Steve

 

[90lxcoupe]

my notch has 275/60's on it here are some pics, i have a 3.73 gear in it now and i am thinking about swapping 4.10's or 4.30's in also

 

[Michael Yount]

"I understand that the taller tires change my effective gear ratio. just not sure what do do about it??"

Easy - up the numerical rear gear ratio or shorten the tire diameter. According to your dyno numbers, if you have the traction to manage the launch, you ought to gear the car so that you're going through the lights in 4th gear at about 5200-5600 rpm. If your trap speed is 102 now - with more effective gearing you're liable to pick up a mph or two. So do the calcs for what gear is needed with a 28" tire, so that (say) 105 mph occurs at 5500 rpm in 4th gear. I calculate that a 4.30 gear will give you 106 mph in 4th (1:1 ratio) with a 27.8" tall tire (the calculated height of your 325-50-15's). That gear should allow you trap somewhere between 100-106 mph at 5000-5600 in 4th gear. Just be ready to pull those 1-2 and 2-3 shifts a bit quicker than you did before. Alternatively, you could keep the 3.73's and move to a rear tire that's about 25.6" tall (stock Mustang height) and that would allow about 107 mph at 5250 in 4th. It's the tall tires that have 'shortened' your gear ratio as you know - you either need shorter tires, or more gear. If you want to see what it's like - perhaps you've a buddy that will loan you shorter DR's for a run or two to see what it does. If you like it, but like your size tire better - then swap in the bigger gear and use it with your 325's.

 

[Pops Fun]

Hi,
Thanks for the info, don't know what I'll do yet probably change the gears...

Steve

 

[hllon4whls]

Just for a comparison, 4.30 with a 28 inch tire puts me through the lights right at 6500. My trap speed is typically 117. With the muffs I trap at about 116, but not quite sure of the RPM.

Also as a rule, a taller tire will put more of the tire on the ground than a shorter tire of the same width. For example if you have a 26 tire that the tread is 10 inches wide (measured) vs a tire that is 31 iches tall measured 10 inch wide. The 31 would have more rubber on the track.

This is why too much tire tends to slow people down 1 it changes the overall drive ratio and 2 there is more drag from more rubber being on the ground.