BFG DR's: 26" or 28" for my combo?

[jaymac]

I posted before about my timeslips, but basically, I was running out of RPM's at the top end @ 96 mph @6000ish (stock tach), on my 255/35/18's and 4.10's (AOD).
I'm switching to a 15" BFG DR, and now I'm trying to decide between the 275/50 (26"), or the 275/60 (28").
I also have to find out if the 2" will fit w/ my 2" drop in the rear.
Which size do you guys think will most benefit my 1/4 performance, considering my mods?

BTW, those 1/4 times were gotten w/ 60's in the 2.7-2.4 range
Thanks,
J

 

[wyominghotwheel]

if it was me, i would just go with the 26", but that is just me........


hotwheels of insanemustangs.com

 

[jaymac]

I "think" my current tires are 23" tall, so I think 26" would be good for me, but do you think it would fit on my car w/ the 2" drop?

 

[USMC1966]

255 35 18 is 25.03
275 50 15 is 25.83

So not very much taller. You tach is might be off.

 

[maverick0716]

What's the gear ratio for 3rd in AOD's....is it 1:1? If it is then you're only actually turning 5200 rpm through the traps.

 

[jaymac]

New question:
I measured my current tires to be about 25" w/ 40ish psi.
Does anyone know from experience if 26" tires will fit on my car w/ my 2" lowering springs?
There's def. an inch of clearance up under the wheel well, but not alot at the lip. I'm just concerned if I went w/ a 275/50/15 (26.1" according to BFG), that I'd have to roll the lip.
Also, I have to find out what the width of the wheel I'm planning to use is.
If it's not at least 7.5, I might have to go w/ the 235/60/15 (still 26.1" says BFG).
The tread width on the 235 is 8", and 10" on the 275.
How much traction do you guys think I'd lose going w/ the 235 instead of the 275?
Thanks!
J

 

[N8Miller]

i would keep the 26s and install an aftermarket tach too.

 

[Stang8URMPRT]

Yep, I'd get the 275/50s... 26 inch tall. The 275/60s took some major cutting and pounding with a BFH to get them not to rub on my 83

 

[jaymac]

OK, new question: I'm also considering a 235/60/15 (26"), as I'm not sure if the rim I'll be using is wide enough for the 275's. Do you guys have any idea how much traction I'd be sacrificing if I went w/ a 235 over a 275?

 

[Stang8URMPRT]

I had my 275.60s on some old 15X7 rims. They will be fine. Sure they'll be a little wide on the rim, but they'll look nasty!

 

[maverick0716]

Mounting a 275/60/15 on a 7" wide wheel is a lot different than mounting a 275/50/15 on the same wheel. The sidewall height makes a big difference on how the tire fits the wheel.

 

[jaymac]

so what are you trying to say?
Will a 275/50 fit well on a 7" wheel?
Or no?

 

[maverick0716]

so what are you trying to say?
Will a 275/50 fit well on a 7" wheel?
Or no?

I'm saying no, it won't fit well.....that is a fact. BUT that doesn't mean that it won't go on the wheel....it just won't have near the amount of grip that it would have on an 8-9" wheel.

I have 235/60/15 MT ET Street Radials on my old 10 hole wheels (15x7) and they fit perfectly.....they look to be about a 245 really. I have heard of several cars going mid-high 12's with that size tire on.

 

[jaymac]

how do you like the 235's performance and grip?
Have you ever SEEN anyone run on a 235/60?
Now, what do you think the difference would be between a MT ET SR width and a BFG DR? I know different companies actually measure diferent widths even though they have the same #'s...
Any ideas?
Thanks, BTW

Also, what's the best 60' times you've cut w/ those 235's?

 

[TheUser]

There is no way I would mount a 275 tire on a 7" wheel no matter if it's 50 or 60 series. 275mm=11 inches, so you're mounting an 11" tire on a 7" wheel. Generally don't want more than 2 inches of bulge (I've actually heard 1 inch).

I have 235/60's on some draglites. Recently purchased a set of 15x10 draglites w/ 275/60's...absolutely huge! By huge, I mean tall...I'm gonna buy some 275/50 BFG's.

Here are a couple pics of the 275/60's just for grins:

 

[Stang8URMPRT]

Worked fine for me for many many trips down the track, Mr. User. And I ran them on the street for about a thousand miles. 275/60/15s on 7 inch rims. Sure, it's not gunna corner for sh it.. but it will work. There is no question about it, seeing I did it for quite some time.

 

[maverick0716]

how do you like the 235's performance and grip?
Have you ever SEEN anyone run on a 235/60?
Now, what do you think the difference would be between a MT ET SR width and a BFG DR? I know different companies actually measure diferent widths even though they have the same #'s...
Any ideas?
Thanks, BTW

Also, what's the best 60' times you've cut w/ those 235's?

Can't say I haven't really got a chance to use them. There's not a whole lot of difference in width between the BFG's and the MT's.....but if one is slightly bigger, it's the MT's.

 

[TheUser]

Notice I said "There is no way I would mount a 275 tire on a 7" wheel no matter if it's 50 or 60 series." I didn't say STANG8URIMPORT wouldn't, I said I wouldn't. That's why I bought 15x10's for my 275's. It's my personal choice. Sure you CAN put them on there, but yes, it probably won't handle very well and isn't necessarily safe. YOU do what YOU want, fine by me. All I'm saying is you might get better handling/tire wear by matching your tire with your wheel.

I'm not trying to start anything, just giving my opinion.

 

[Stang8URMPRT]

My bad... I thought ya said you couldn't. My fault. I'm the ass here.

 

[Michael Yount]

jaymac - you're going through lots of stuff here on the assumption that you're running out of revs. The factory tachs are notoriously inaccurate - I doubt that 6000 on the stock tach is right. You're likely well short of that rpm level at 96 mph even with your tire choice.

I'd get an accurate tach LONG BEFORE I ever invested the money in different tires. Get your data correct before you start making decisions based on incorrect data; then you can make a wise choice about tire height.

And the User is spot on regarding tire size/wheel width issues. Those of you mounting too wide a tire on too narrow a wheel are kidding yourselves if you think you're getting the entire tread width on the ground with a full contact patch. You can put a wider tire on the car, but if the wheel's not wide enough to spread the tire appropriately and support the sidewalls, you're not getting much more contact patch on the pavement. So why use the wider tire?