tire pressures

SkipB · #1 (**permalink**) 10-20-2007, 04:43 PM

I know this has been covered before, but I really would like some input from Backdraft owners ONLY on what the optimum tire pressures (F&R) are for the 15" wheel set up with BFG Radial TAs. Because we have a BMW based suspension, input about other car brands is not so useful.

I am looking for the best all around set up for the street. I don't do any competitive events, especially with these tires! I just want great handling, limiited vibration, and the best ride. Not much to ask!

SkipB

Naumoff · #2 (**permalink**) 10-20-2007, 05:58 PM

Quote:

Originally Posted by SkipB

I know this has been covered before, but I really would like some input from Backdraft owners ONLY on what the optimum tire pressures (F&R) are for the 15" wheel set up with BFG Radial TAs. Because we have a BMW based suspension, input about other car brands is not so useful.

I am looking for the best all around set up for the street. I don't do any competitive events, especially with these tires! I just want great handling, limiited vibration, and the best ride. Not much to ask!

SkipB

http://www.backdraftboys.com/forum/

SkipB · #3 (**permalink**) 10-23-2007, 10:29 PM

Guys,

I can't seem to get on the Backdraft Boys site and I am dissapointed that the only reply is from a Unique owner.

So, I still need some help on the original question.

SkipB

Naumoff · #4 (**permalink**) 10-24-2007, 03:37 AM

Skip,
I run 24psi rear and 26psi front in 295/50 15 and 235/60 15

I copied this from a thread on the Backdraft site.

Quote:

While checking out BDR473 upon arrival, the air pressure in the 17" Goodyear F1 tires varied from 23-28 psi for the four tires. The manual for 473 indicates 28 psi front and 29 psi rear. As phone calls are cheap on cell phones these days, I called Backdraft in Boynton Beach and they recommended what the manual indicated - 28 psi front and 29 psi rear. I filled the tires to these tire pressures and the ride appears OK. I have had a minor tire scuff on the bottom inside of the left rear fender well; this happens if I go over a short dip in the road and the car goes up and down fast. Leaves a minor scuff on the edge of the F1. Nothing on the right side.

See if this link will take you to there site.I am surprised Jay or Reg haven't responded to this thread. They are usually good about that.
http://www.backdraftboys.com/forum/t...sp?TOPIC_ID=20

Cashburn · #5 (**permalink**) 10-24-2007, 05:47 AM

It's been posted on this site before, I believe the consensus from several owners with the 15" tires was that 28psi all around is nice. Our experience is primarily with the 17" wheels, in fact the 15" wheels only account for 15% of our sales.

SkipB · #6 (**permalink**) 10-24-2007, 10:43 AM

Thanks guys for the responses.

I'll try a couple of the settings mentioned. The reason I asked is a couple of guys around here are running really low (20-22psi) in the rears and say this works well. It sounds too low to me! 28 or so sounds better, and safer.

SkipB

Ps. I finally was able to get on the Backdraft Boys site. Not too much on tires there except for 17" info.

rdorman · #7 (**permalink**) 10-24-2007, 12:54 PM

For what you are asking, the BMW based suspension really doesn't mean any thing. Unless BDR has tested your setup on your tires and come up with a recomendation (did you ask them) then you are asking for some one else's personal preference. BFG has this formula:

(Vehicle Weight in lb/100) + 2 psi at heavier end + 2 psi all around if suspension and alignment are stock.

Example: 2800 pound car
(3000/100) = 28 psi
Add 2 psi all around = 30 psi
Add 2 psi to heavy end = 32 psi at rear

Many find that high, put plug in yours numbers and see what you think. Play with them up and down a few pounds and try again. Have fun!

Naumoff · #8 (**permalink**) 10-24-2007, 01:57 PM

Rick,
That is awlful complicated.

SkipB · #9 (**permalink**) 10-24-2007, 08:17 PM

Ok, lets do the math here.

3000 divided by 100 = 28? Not in my fire torn San Diego county.

Tell me by that formula what a Backdraft weighing 2400lbs would run at both ends.

SkipB

pgermond · #10 (**permalink**) 10-24-2007, 08:45 PM

Had my car weighted by a Winston cup team member (a scale on each corner) - set-up with 26lbs fr & rear.

Slick61 · #11 (**permalink**) 10-24-2007, 09:21 PM

man... y'all got some heavy cars... mine weighs in at 2240 lbs. I've got the Radial TA's, & run 26 all around. So far, I'm happy with it.

rdorman · #12 (**permalink**) 10-25-2007, 05:27 AM

Quote:

Originally Posted by SkipB

Ok, lets do the math here.

3000 divided by 100 = 28? Not in my fire torn San Diego county.

Tell me by that formula what a Backdraft weighing 2400lbs would run at both ends.

SkipB

Oops! You seem to be able to do the math, I am sure you will have no trouble! FYI, many are heavier in the rear.

cbreez · #13 (**permalink**) 10-25-2007, 05:45 AM

guys....26-28-30????
are you splitting hairs here? maybe?
these a lightweight cars with street tires...anyone of those previously discussed numbers will work....personal perference and tire wears trends should dictate which you prefer....just don't exceed the max imprinted on the tire.

mpanten · #14 (**permalink**) 10-25-2007, 07:17 AM

Quote:

Originally Posted by cbreez

guys....26-28-30????
are you splitting hairs here? maybe?
these a lightweight cars with street tires...anyone of those previously discussed numbers will work....personal perference and tire wears trends should dictate which you prefer....just don't exceed the max imprinted on the tire.

No, 2-4 punds can make a big difference. Most people run around 24-26 lbs with cobras in that weight range regardless of the make.

cbreez · #15 (**permalink**) 10-25-2007, 07:59 AM

if one can truly and honestly "feel" the difference in 2 lbs of air (even 4 lbs) driving around on the streets, you must be a real sensitive guy!
Good luck to all in beating this dead horse!

mpanten · #16 (**permalink**) 10-25-2007, 08:04 AM

No you cant feel it when driving around on the street but you can notice it when you turn. And yes sitting on my but for a job for the last ten years tends to make ones gludious a bit more sensitive not to mention bigger

Bx1 · #17 (**permalink**) 10-25-2007, 10:13 AM

I am so sensitive I missed 2 days of work due to a paper cut to my finger....
but in all seriousness... it seems to me that 26 PSI air pressure is at the very low end of the spectrum for our cars. I have heard the theory of 1 PSI per100 lbs. of car weight but does that hold true just for Cobras? If so, why?
I have 28 PSI front 245/60/15 and 30 PSI rear in YOKO's S/T 295/50/15. I would like to hear a solid reason why lower air pressure is better.

Barry Hall · #18 (**permalink**) 10-25-2007, 01:42 PM

I've got the 15" BFG radials on my BDR. Geez, hate 'em being so Squisshy....I run all 4 of mine at 33 psi. Love the firm ride, no wallowing feel from the tall sidewalls.

SkipB · #19 (**permalink**) 10-25-2007, 02:12 PM

Well, I guess I am a sensitive guy. I can feel the difference in just a few pounds of air, especially on the low end. I see we have thoughts all over the place, but it seems like mid to high 20s wins out.

I would really like to replace my BFG TAs with something a little more round, and sticky. I know the selection is limited. Next time I am going to try the YOKOs. That seems to be the way to go.

So no more beating a dead horse, even if there are many different set ups. I was just assuming that the Backdraft guys would have an optimum set up from experience and multiple attempts to get it just right. Guess I was wrong!

SkipB

SkipB

Naumoff · #20 (**permalink**) 10-25-2007, 02:45 PM

This is not beating a dead horse. It can give someone a place to start.
If the Club Cobra forum isn't here to help other Cobra enthusiast then what is it for?
I did a search on tire pressures and it took a few tries to get to something close to what would help.
The search feature ain't the greatest and if all these repeat questions bore you get another hobby.

Any teachers hear? I guess this attitude would be great for the people teaching are children. I can see it now.

Sit down kid and shut your mouth. You are beating a dead horse. Do you know how many times I have been asked that question?