Widest tires on OEM's

Pretty much the largest tire I have seen tire manufacturer's recommend on a 17x8" rim is 255. The problem with that is it is also a bit taller so it will throw off your speedo. I posted 3 links earlier in this thread, take a look. Yes, mounting a tire designed for a wider rim can cause the edges to wear faster than the center.
 
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I did look at the "approved rim width column," Bob. My point is that I have those tires, those very same Cooper Zeon 275/40 tires, on my OEM rims and they fit just fine, no problems whatsoever, and that fact might prove helpful to the gentleman who began this thread. :nice:
 
I would have to say the manufacturer of the tires would disagree with you. What is your criteria for "they fit fine"? Just because they can be mounted on an 8" rim by no means indicates they will work fine. The manufacturer didn't just pull those specs out of thin air or make them up on a whim. If you chose to second guess the manufacturer, that is your perogative. I just have a problem in suggesting others do the same without giving them all the facts.

Here is a disclaimer from Yokohama's web site regarding what can happen when choosing a rim outside the manufacturer's specs.
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Each Yokohama tire has a specific rim width range on which the tire can be mounted. Failure to follow rim width recommendations may result in poor tire performance or possible wheel and/or tire failure.

Below is a quick reference chart listing each Yokohama tire size and the acceptable rim widths for that size. Choosing a wheel near the middle of the range will give a balance between ride quality and handling. A wider wheel will improve handling at the expense of ride quality, while a narrower wheel will improve ride quality at the expense of handling. Consider these compromises when selecting wheels.
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MotleyCrue said:
I just want a clear answer, 04 GT, stock rims, whats the largest tire width size i can go out back.

I guess it depends, do you want to go with something within the manufacturer's guidlines or do you just want to stuff the largest tire you can on the rim :shrug:

What tires are you looking at? Every manufacturer lists the specs/sizes for their tires on their web sites.
 
MotleyCrue said:
I just want a clear answer, 04 GT, stock rims, whats the largest tire width size i can go out back.

A lot depends on several factors. One being the rim in question. It is the Premium rim or one of the other OEM offerings? Also, the tire in consideration. Tire makers rate tires different ways. Anticipating Bob's reply, yes I know there is an industry standard, but like most other companies, there is a built in safety net, so recommended rim width may actually be increased as a preventive measure. For example, I believe the published OEM rim width for the Premium rim on my Mustang is 8.00. It measures between 8.50 and 9.00. So, speaking from personal experience, I have a 2003 GT Mustang, Premium Edition and the Cooper Zeon 275/40/17 fit nicely without any problems. No bulging, warping, or change in ride. Furthermore, it has a great tread design and Cooper is a good, old, solid name in the tire industry unlike many now popular tire comapnies flooding the market. Ultimately, the choice, or choices, are yours to make. Good luck and let me know what conclusions you reach.
 
03gtstangguy said:
A lot depends on several factors. One being the rim in question. It is the Premium rim or one of the other OEM offerings? Also, the tire in consideration. Tire makers rate tires different ways. Anticipating Bob's reply, yes I know there is an industry standard, but like most other companies, there is a built in safety net, so recommended rim width may actually be increased as a preventive measure. For example, I believe the published OEM rim width for the Premium rim on my Mustang is 8.00. It measures between 8.50 and 9.00. So, speaking from personal experience, I have a 2003 GT Mustang, Premium Edition and the Cooper Zeon 275/40/17 fit nicely without any problems. No bulging, warping, or change in ride. Furthermore, it has a great tread design and Cooper is a good, old, solid name in the tire industry unlike many now popular tire comapnies flooding the market. Ultimately, the choice, or choices, are yours to make. Good luck and let me know what conclusions you reach.

Your rim width is actually 8.00" +- .02"

The rim width is measured from the intersection of the beadseal and the inside flange...on both sides. There is no anticipated buffer for larger tires. Thats not to say I disagree with running a slightly larger tire than recomended...but it's definatley not according to the tire and rim associations standards to have a 275mm tire on a 8" wheel.

BTW, I have 275 nitto's on my 96 cobra rims and love them :nice:
 
03gtstangguy said:
A lot depends on several factors. One being the rim in question. It is the Premium rim or one of the other OEM offerings? Also, the tire in consideration. Tire makers rate tires different ways. Anticipating Bob's reply, yes I know there is an industry standard, but like most other companies, there is a built in safety net, so recommended rim width may actually be increased as a preventive measure. For example, I believe the published OEM rim width for the Premium rim on my Mustang is 8.00. It measures between 8.50 and 9.00. So, speaking from personal experience, I have a 2003 GT Mustang, Premium Edition and the Cooper Zeon 275/40/17 fit nicely without any problems. No bulging, warping, or change in ride. Furthermore, it has a great tread design and Cooper is a good, old, solid name in the tire industry unlike many now popular tire comapnies flooding the market. Ultimately, the choice, or choices, are yours to make. Good luck and let me know what conclusions you reach.

This is just plain :bs:, where do you get this stuff? The published rim width is 8" because that is what they measure. As has already been stated, you measure a wheel from bead seat to bead seat.
 
I have made my points, I am not going to continue to beat my head against a brick wall with someone who will say anything to justify their decision. You are flat out ignoring the manufacturer's specs and rationalize it by saying nothing has happened to you so it must be ok.

I am outta here :rolleyes:
 
I've got stock 17x8 01 Cobra Rims and I run 255's front and 275's back. I've been running 275's in the back for 2 years and haven't had any problems. Like what has been said, there are lots of specs here and there, but there are also a lot of people on this forum who have put 275s on with no probs. I was hesitant, but when I read up on here how lots of people have been doing it, I felt better. It actually lessened my wheelhop when accelerating.

The only gripe I have is that you can't rotate your tires and you wind up replacing them sooner. BF Goodrich KDW only lasted a year for me in the back. I switched to BF Goodrich KDWS when I replaced them since they had a higher tread rating. 255's look nice, and if I could go back, I would put 255's all around just so I can rotate them. However, I'm currently looking for new rims and am going to put wider rims in the back, so I guess I'll be stuck with not being able to rotate from now on :)
 
2001 Geee T said:
I just happened to be at the tire place today picking up someone so I asked about tire sizes on the 8" rim. He said if you go 265 or higher it will bow the contact pacth of the tire and you wont be getting the whole tire to the pavement. Is this true?

That's absolutely true. If you go beyond a certain size tire on a particular rim, you end up with LESS contact patch. You see this all the time on motorcycles. Guys are all trying to get more contact patch, so they just stuff on the biggest tires that will clear the swingarm. They end up completely screwing up the handling and get less tire on the road to boot. But they insist that the fat rubber "looks cool."

I am not sure what the exact number would be for an 8" rim, but I would feel pretty safe going by what The Tire Rack says. Those guys are pretty serious about their stuff, and have been experts on upsizing for years.
 
Bob, I know how to read a set of calipers, and my rims are wider that the published 8.00. I also had it checked by a Dobbs Auto representative before I made the decision to purchase the 275/40's. He got the same measurement. Now, as for how these rims are what they are, I have no clue, but I do not appreciate being called a liar. Don't be so anal retentive that you cannot learn something from someone who has different facts than you. Also, I have no problems with decreased tread contact with the roadbed. They run flat on the roadbed and true all day long. Like I said, my car can be seen daily tearing up the streets in St. Louis!
 
03gtstangguy said:
Bob, I know how to read a set of calipers, and my rims are wider that the published 8.00. I also had it checked by a Dobbs Auto representative before I made the decision to purchase the 275/40's. He got the same measurement. Now, as for how these rims are what they are, I have no clue, but I do not appreciate being called a liar. Don't be so anal retentive that you cannot learn something from someone who has different facts than you. Also, I have no problems with decreased tread contact with the roadbed. They run flat on the roadbed and true all day long. Like I said, my car can be seen daily tearing up the streets in St. Louis!

Like I said before, on a stock 17X8" oem wheel, the machining tolerances are
+- .02". Then only way you have a wheel that is larger than published is if you have either a knockoff that is not oem, or bought them from someone who had them widened. Read my above post for the proper way to measure a rim width.
 
rjstaaf said:
I have made my points, I am not going to continue to beat my head against a brick wall with someone who will say anything to justify their decision. You are flat out ignoring the manufacturer's specs and rationalize it by saying nothing has happened to you so it must be ok.

I am outta here :rolleyes:

rjstaaf, you ve been right all the way trough this thread. The widest tire you can fit on 8 inch rim according to probably all the manufacturer out there is a 245. A few ones will tell you 255.

And BTW, having larger tires just for the look is just lame. Dont mess with the only thing that gives you contact with the freaking asphalt.
 
I agree with the guys saying to look at what the MANUFACTURERS recommend. I mean good grief, they pay ENGINEERS to figure out what tires will do and how they will perform the best. When they recommend something it is because it WORKS and PERFORMS the best. Just because you can get a wide tire to somehow fit doesn't mean you should do it. And just because some people have made them fit I really doubt that they are getting the fullest potential from their tires as say someone who has the right width on the right rim. But I know those people will continue to say well I got it to work so it must be good. Me, Im going to listen to the engineers who get paid to design performance tires.