Widest 16" tire, on stock rim

[68COUGAR]

What is the widest tire you've put on your stock 16" rims? 255/50/16's are the biggest I've seen. Anybody have anything wider?

Curious 68COUGAR

[Deep6]

Without any major rubbing of course. SOME 255 series tires do rub a little though, so it depends on the manufacturer.

I'd be more curious to note any handling discrepencies that folks have noticed running that series tire.

[68COUGAR]

Well, I've run BFG 255/50/16 Comp T/A's on the front & back of my car. NO interferrance.

Just for the record, BFG's have a Very Stiff sidewall. That's one reason why they are such a Superior Road Handling Tire!

68COUGAR

[DamonSlowpokeBaumann]

Hey cougar..Is your car lowered?..I was thinking of teh 255's but was worried about rubbing with my car being lowered 1.5 inches

[DCClark]

I run Dunlop SP5000's AS, 255/50/16's no rubbing here either. The dunlops also have a very thick sidewall, which is needed when oversizing the tire width wise. I had some goodyear eagles, and for some reason their sidewall was crap. At around 145 (mounted, balanced) they are a good tire. They are sipped, and provide excellent traction rain or dry.

[68COUGAR]

I wish I could lower my car, but I've got the Big Dawg exhaust. It already drags when I go through a dip & compress the suspension. The center hangers were 3.5" to short, so they ended up sitting on the tranny cross member!

68COUGAR

[danekejt]

hey 68COUGAR

how do you like that big dawg exhaust? do you have any audio clips of it? is that the one that is on the ttp://www.supercoupeperformance.com.

[68COUGAR]

Good Points!

(1) Flows like a sewer pipe
(2) No Back Pressure
(3) Works well with reground cams

Bad Points!

(1) Doesn't Fit Well
(2) Center Hangers to short
(3) Kinda Buzzy
(4) Kinda Loud
(5) Hangs Low (see #2)

Overall, I like it. I got it cuz I didn't want to blow HG's any more. The lower the backpressure, the less likely you are to blow HG's. I also put SCCoA coated headers on.

[sc steve]

I am running Kumho Ecsta Supra's (sp) 245/50ZR16's and have no trouble yet;) but then again I dont see why I would if you guys are running 255's

[Deep6]

Too much sidewall flex or does the strength of the side wall make up the difference?

[68COUGAR]

The stiffness of the sidewall has a LOT to do with how the tire preforms. BFG's have a very still sidewall. That means that they corner Very Well, but do not absorb drive line shock well at the strip. A soft sidewall tire, will roll under when pushed hard, but will absorb alot more drive line shock at the dragstrip.

If you're not sure what drive line shock is, think of what happens to the tires on a Top Fueler at the line. Those incredible sidewall wrinkles are caused by driveline shock.

68COUGAR

[Deep6]

I know what "wrinkley's" are. But what I'm curious to note is how well a 10" wide width tire (IE. 255 series tire) works on a 7" wide rim (IE, our stock SC wheels)

That tells me that you'd have about 1.5" of "doughnut" look on each side of the tire, when you'd stick a 255 series tire on that rim. Did anyone here who's put a 255 series tire on their car notice adverse handling issues like Too much sidewall flexing, or would BF goodrich tires, (with their very stiff sidewalls) stand up to the abuse? Since I"m considering the BFgoodrich G-Force KDWS tire as my mainstay, I'd like to run a 255 series 17" tire on a 7" rim. I have no choice to go to a larger rim.

[DamonSlowpokeBaumann]

Id have to say it wil regardless of sidewall stiffness adversely affect the handeling..You want the look..Go 255..You want teh handeling...Go smaller:O)

[68COUGAR]

I'm curious as to why you think a 255 tire will not handle as well as a 245 or smaller tire? The difference between a 245 & 255 is less than half an inch!

As far as the "donut effect" goes, would you use a 178mm tread width? Probably not, but that's how wide a 7" rim is. So you see, even the OEM 225/60/16's were wider than the rims.

A lot of aspects affect a particular tires ability to perform well, Weight of Vehicle, Tread Compound, Sidewall Stiffness, Tread Width, Aspsect ratio & yes Rim Width.

68COUGAR

[XR7 Dave]

Manufacture's recommended rim widths means about crap. They all say that a 7" rim is ok for a 255/50. All that means is that it will go on. It does NOT mean that proper performance will result.

If you want the best handling performance, then you start by selecting a tire whose TREAD width closely matches your rim. Remember, tires are sold by SECTION width, not tread width.

Example #1:

Stock tire 225/60/16 tread ~ 8.0" recommended rim width 6-9"
Stock wheel: 7"

So, our rim is a little on the narrow side already, but well within range.

Example #2:

255/50/16 tread ~ 9.5 recommended rim width 6.5-10"

MmmmKay.

Example #3:

Stock tire 275/40/17 tread ~ 9.8" recommended rim width 9-11"
Stock wheel: 9.5"

Hmmm. Good match. Any guess what car this is on?


Some pointers when selecting tires. Regarding the tire itself, carcass construction and tread compound are primarily responsible for the dry weather handling performance. Tread design is of secondary significance unless it is just WAY off.

In order for the carcass to perform as intended, it MUST be properly supported by the right sized rim. A stiff sidewall on a wide tire and a narrow rim will result in very premature wear in the center of the tire, as well as a wishy washy feel COMPARED to the same tire on the right sized rim.

Selecting a soft sidewall tire of the same size for a narrow rim will help both of the afore mentioned problems, but will give poor cornering traction as the sidewalls roll easily. So if you do not, or can not select the proper rim and tire combination, then handling will be poor COMPARED to what it COULD be if you had the "right stuff."

Also note:

Dunlop SP8000 255/50/16 section width 10.0", tread width 9.4"
BFG CompT/A HR4 255/50/16 section wicth 10.4", tread width 8.4"

All tires are not made equal.

[fast Ed]

Good explanation Dave, this is what I've been trying to get through about on another thread.


cheers
Ed Nicholson
SCCoO

[Deep6]

Great explanation Dave. All I was trying to do was guage performance based on those who have "been there done that" kind of a scenario.

Since no one that I know who's mounted a 255-45-17 tire to a 7" rim, I thought that I might be able to extrapolate feedback based on those who have mounted a 255-50-16 on their stock 7" SC wheels.

255 technically being a "10.0" tread.

So my mental dilemma had been "others have mounted 255 series rubber to a 7" wide wheel, why can't I"??

It'll mount and It'll work and even improve performance, but not as much as if I had mounted it to a rim of the proper width.


Interesting point Dave, how are you able to tell which manufacturers produce varying tread widths based on the same section width?

[XR7 Dave]

I would say no, don't try to put a 255/45 on a 7" rim. First, let me pull up a couple of examples.

Example #1: BFG 255/45 rec. rim width 8-9.5 tread width 8.2"

Example #2: Kuhmo 711 255/45 rec rim width 8-9.5 tread width 9.3"

Neither tire is recommended on a 7" rim. Notice that the two examples vary in TREAD width by more than an inch! However, the key to the whole thing is, that the shorter the sidewall of the tire, the less the tire can accomodate an incorrect rim width.

I think you missed my whole point earlier. Think about the geometry for a minute. If an ideal tire/rim combination draws a veritcal line from the edge of the tread to the lip of the rim, then if you put a wider tire on a narrow rim, then an angle is created from the crown of the tread to the rim. The wider you go, the sharper the angle. Likewise the lower the profile, the sharper the angle. Angles are bad. Tires are not made to work with severe angles (well except for cantelever slicks, but that's another story!). It makes all sorts of bad things happen. You may very well find that handling is NOT improved over the stock size. It will feel different for sure, but I would NOT count on it being "better," of course that also depends on how you quantify "better."

A 255/50 has much more sidewall to work with than a 255/45, and on the 255/45 there is a much higher percentage of the sidewall made up of Bead Filler, which is a very hard, non-compliant rubber. The result is a tire that is not very forgiving in terms of rim width.

Did you also notice from the examples that some 255/50's list a 6.5-10" rim width range whereas the 255/45's list only 8-9.5? This supports what I am saying.

I'm not saying you can't do it, and there will always be some one who will tell you it works great, but you are the one who will have to live with the result.

Do the right thing, get some 235/50/17's and be done with it. Your car will handle well, the tires will wear even, you will get great tread life, it will look good, and you won't have issues with balancing (yes it is hard to get an oversized tire to mount up true and balance properly).

Example: Firestone Firehawk 235/50VR17 Treadwear rating 500AA Tread width 8" section width 9.7" Diameter 26.3" recommended rim size 6.5-8.5. Price $122 at Tire Rack.

There are others, but this is a decent example. I don't know what else to say expect if you want to get the wrong size tire, you will always find someone who will sell them to you.

[Deep6]

I guess you've been able to to explain it a little bit better than what I had been processing in my brain earlier.

You're example with the firestone Firehawk tires opens my eyes a bit. MY goal here of course is multisided I want everything basically. The rims I'm looking at ONLY come in a 7" rim width. At the same time I'm looking to mount the largest "patch" I possibly can. Run the same size at all four corners. Run a "all-season Z-rated tire" and do it without going crazy.....

Even though I've checked out "discount tire.com" when I checked out a competitor's rim (enkei RS5) it was a 17x7" rim. Recommended tire sizes (according the web page) for the BFgoodrich G-force KDWS was 235, 245 and 255 series rubber.

Ed disagrees with me here, but for the cost and availability, the Centerline Rotary Forged Rim is a 17x7" rim with a 42mm offset and weighs a mere 13.5Lbs. That enkei was lightweight but still weighs in at 16-17lbs.

SO you see, I'm a basket case here, I'm looking for a wide contact patch to increase grip, shorter sidewall to improve handling feedback, All season Z-rated tire for better performance than my stock tires (even though I DO realize that dedicated summer tires would do a better job in the dry), reduce unsprung weight, match the T-birds retarted bolt pattern and do it for a reasonable cost.

But anyway dave, thanks for the recommendation. BTW, what is the stock width contact patch of our stock tires?

[XR7 Dave]

The stock tires were about 8" which is wide for a 225/60. A lot of replacements out there now are down as low as 6.5. It varies a lot. You are going to be looking for about 8" of contact area. Much more is going to result in a distorted contact patch.

Check out the specs at tirerack.com. You can compare most all tires there. Depending on which tire you go with, you could go with anwhere from a 235/45 (which is shorter) to a 225/50 (which is a little taller) and also consider 235/50, and 225/55. From a handling perspective the 235/45 will be better IF you get the right ones. For example Michelin's like a narrower rim and have a smaller footprint (notice that they don't advertise the foorprint?) whereas that size in a Bridgstone wouldn't be a good idea at all. Keep in mind also that BFG's are a cheaper Michelin (same company), as also Firestones carry the same basic carcas as Bridgestones only cheaper.

High treadwear ratings are a double edged thing. 400 is great for wear, but dry traction will suffer and the tires will "squeal" where as a 220 will have much better dry traction and will be quiet under stress, but won't wear as well.

Have fun comparing specs, I did, although there are too many to list specific examples here!

David

[Deep6]

It seems that regardless of P-metric number (ie 225, 235 245 etc) actual tread contact patch can vary by quite a bit. With a 'new' specification like that for me to shop with, I might be able to pick the proper sized p-metric tire (as you recommend, the 235/50/17 sounds good) but still have a wider contact patch than stock...well maybe.

I didn't know that about BFgoodrich tires. I did know that firestone and bridgestone were the same company and therefore the tires shared technology. Thanks for the heads up on that. I've seen that the michelins are amongst the most expensive tires. maybe I ought to look at something cheap like the Kumhos, HanKooks or Sumitomos....