Hi everyone, what are the pros/cons of "stretching" slim tyres to fit a wider rim?

the reason i ask is i recently got some new tyres put on my 18" wheels. These are the first tyres i have bought for my FD.

Call me stupid or whatever but basically i asked for the same size tyres as were on there currently (i figured that they must be the correct size as thats what it had on before,. and i didnt knnow the actual width of the wheel)

ok so all is fine, and i put 18x225x45 tyres on my 9" wide wheels. I drive around on them for about a month not thinking anything of it...
Some time passes and im in a tyre shop getting a tyre removed from a wheel so i can take it to a machine shop to get repaired. (went over a really bad pothole and the lip slightly bent) while im in the tyre shop the guy asks me why i have these tyres on these rims -- i tell him thats what it had on when i got the car, so i got the same size tyre again..he tells me he is surprised the tyre shop would even put that width tyre of that wider rim............interesting...............

So basically i have 9" wide rims with 225's on them..
what are the pros and cons of this? thats for any info -- much appreciated.

 

I don't have time for a direct answer to your question but Lots of good info here from experts:
http://www.tirerack.com/tires/tiretech/tiretech.jsp

 

its fine.

you wont die.

ive driven thousands of miles both street and track with stretched tires (215/40 on a 17 in front, 225/45 on a 9.5 in back) and never had a single problem.

its really an issue of style, if you like the look of stretch, then stretch your tires, if it looks dumb to you, then run the suggested tire size.


im sure a bunch of "real performance" jerk offs will tell you othrwise. but they are wrong, plain and simple.

you will be fine.

 

I'm not surprised at the tire guy's reaction my car has 7" wheels with 225s on them, FDs run 225s on the stock 16x8" wheels. As far as I know the only advantage you get out of it is less tire distortion at the cost of having a really skinny tire when you could probably have 255s under there and have much more overall grip.

 

225 on a 9 is hardly a stretch. imo its just as retarded (for some people) to feel the need to run 285s all around on a street car thinking its giving them some sort of advantage.

but anyway,you WILL die. be afaraid. be very afraid.

 

Pro - Cheaper tire
Con - Exposes the rims to more street damage

The previous owner could have done it to have a little more aggressive wheel offset and then use a smaller tire to help remove some potential rubbing.

 

Cons - It goes against what every tire engineer has ever reccomended, you'll suffer the concequences of worse acceleration, braking and ride comfort that bigger, heavier wheels give you without the advantages of better grip to make it worthwhile, it exposes the wheels to damage, it looks dumb to most people, people will assume that you're one of "those people", etc.

Pro - I've never seen any compelling arguments to do it, they're all just flimsy arguments to try and justify a style choice.

 

So what qualifies as a "good argument" to justify a style choice? Are you going to shoot holes in people's logic because they prefer one thing over another?

The fact is, 99.9% of the population (that is, the people who aren't autocrossing for national competition) could care less about going around a road course 1 second faster than if they used skinnier tires.

I guarantee you, if you had two identical cars running identical tire sizes, but one car had wheels that were 5 lbs heavier than the other, at least 95% of the people could not tell the difference between the two.

With tires, its easier to tell the difference for sure; but the point is that most people drive for enjoyment; not to post the fastest lap times. And frankly, there's no reason to run the absolute widest tires you can unless you're going after the fastest lap times. Maybe I'm making a huge generalization with this statement, but I feel the people who worry the most about their setup end up improving the slowest, compared to the people who just worry about having a good time.

So what incentive is there to stretch tires over running normally sized tires? I dunno, because its cheaper and you can get that mad baller wheel fitment. Who cares. I think when people go overboard like 195s on a 9" or 10" wheel its getting a little too crazy, but 225s on a 9" isn't bad at all.

I don't stretch tires myself, but I can't stand the elitism people hold just because they're running the lightest wheels possible, the widest tires possible, etc etc... Nothing personal against you Black91n/a

 

A good argument would be something like a performance improvement over going with either wider tires on those same wheels, or over using the same sized tires on smaller wheels.

To me the cheap tires argument is laughable, because much of the time the person just spent big $$$ on big wheels, so the budget clearly isn't a huge concern.

I don't think I've ever made the argument that everyone should be running the biggest tires they can possibly fit on the car, and I don't think that's right for most people. I merely think that they should be running wheels and tires that are appropriately sized for one another and are appropriate for the given use.

In the Miata world it's very common to hear from ordinary people switching from a heavy wheel and tire setup to a lighter one and exclaiming how much better the ride and handling feel. So yes, weight does matter, and ordinary people notice.

I'm no elitist, I run used, heavy Mustang wheels and used STi tires on the street and Rota wheels and race tires that I bought on sale because they're discontinued, but they're sized correctly for each other. I do this because it gave me the best performance that I could reasonably afford.

And yes, 225's on a 9" wide wheel aren't that bad, especially compared to some of the more extreme stretches people do.

 

Just to play devils advocate here.... First, I'm not saying stretched tires are great or that everyone should do it. However, the weight stuff always rubs me the wrong way. The reason is that people keep bringing up "it made a huge difference in my Miata, or Civic"... basically, all these cars that weight about as much as an FD but have 100 or so less horsepower stock (not that you can find many stock FD's around). The Miata power to weight ratio is what 1 : 14.8 or so?

While I agree that unsprung weight is not necessarily good, I don't think it's as much of an issue for:

a) People who aren't competitive or performance driving
b) Cars that have a very good power to weight ratio

I think people on this forum take the "buy light wheels" to the extreme when in 90% of the cases the driver will never notice the difference. In some cases, they will only notice the bad side by buying a light rim which may not be a strong rim to withstand public streets (such as potholes), ala SSR and the people who bent those on public streets.

But if people want to run stretched tires with their rims sticking out? So be it. RX7's are getting cheaper by the day. Younger and younger people are able to afford these cars now so the owner crowd is changing. I have a feeling that most of the old school guys will stop visiting here in the next year or so completely.

 

honestly a 225/45 on a 9 will be fine, the only worry you should have is that the rim might not be sitting inside the side wall and you might have a chance of curbing your wheel easier. Even if you had a 245 you still hold the chance of curbing you wheel so to me it makes no difference. I run a 225/40 on my 9.5's daily and I have no problem at all and I do drive it hard! Being that you have .5 inch skinnier wheel and 45 series vs my 9.5 and 40 series you should have a lot more play in you tires.

 

I used to be a super-anti-stretch-tire kinda guy but I have learned some over time that certain stretch fitments provide a shorter o.d. tire and a more crisp handling feel as well as a more nimble setup and lighter in weight... as just a few of the positive reasons.

I do think some guys go too far extreme for the sake of style and most of those guys know it and dont b.s. about their reasons to look so crazy.

I like 295/30R18 on my 18x10's but theyre much more expensive than a 245/40R18 that wouldnt be too far from the 295 contact patch on the same wheel. if I wasnt searching for traction on 295's with the LS1 swap, then the 245 stretch setup would be a good idea.

 

The REAL problem with those tires is that they are a 45 profile instead of the 40 profile that should be run.

If you want the recommended tire size, from a tire manufacturer and performance standpoint (and appearance standpoint for me), the best size would be 255/35 18. However, without knowing the offset of the wheels or anything else about your car, that size may result in fender clearance problems.

 

pros: easier to fit wide rims in your wheel well, you can lower your car more, and it looks amazing!!!



^^^not my car^^^

Cons: who cares your bout' to be stylin

 

thanks for the replies everyone, much appreciated
Whats the problem with running the 45's ? not disagreing with you just wondering whats wrong with using 45's as opposed to 40's?

I also thought that using 45's would technically make my wheels slightly larger meaning one turn of the wheel = slightly more distance then one turn with a 40 tyre. meaning you can go slightly faster? what is negative about this considering i get no scraping ( i have rock hard hks coilovers! ) thanks

 

While I'll admit that you probably won't die or suffer any dire concequences from running a stretch, I just don't think it's a good idea, or that there's any real improvement that can't be had some other, more sensible way.

Yes it'll be more apparent in something lighter, but it demonstrates the point that average people can and do notice the difference. Sure the difference would probably have to be greater in an RX-7 to be noticable, but lightness is always a worthy goal, as long as you can maintain strength and it doesn't break the bank. Also, much of the difference felt isn't in the car feeling slower, it's in the car feeling more nimble in handling with better ride comfort.

Yes it'll be lighter than a wider tire on that same rim, but it will still be a bunch heavier than that same tire on a more appropriately sized rim. Also, a nice square sidewall where the tire and rim widths are closely matched can and does give very nice feel and feedback. If you really want small o.d.s, get some 15's, you can get some quite short o.d.'s in those sizes.

The problem is that tire size has a larger diameter than stock, the correct diameter tire would be a 225/40/18. Negatives of the taller tires is a taller gear ratio giving worse acceleration, the tires will be heavier and it'll cause the speedo to be off.

 

Jesus

Maybe not everyone is worried about pretending they track their car every day, and wants it to look cool to them?


Am i missing something? How the **** does this same exact thread happen every 2 weeks?

How can a guy who runs ROtas ever talk about "light wheels" like he knows anything?

 

because rotas are light and cheap. I see many old school race cars that run stretch. Back then, tire technology wasnt very good and all tires had soft sidewalls so a stretch improved response. Nowadays, stretch can help response on street tires a lot , but on a max summer or a slick, I think a recommended tire setup will perform better. I can sit on my r888 unmounted and the sidewall wont even bulge. I dont think a stretch is dangerous unless its hyper extreme and you can see the bead seat area with the tire seated...Looks are all preference, I run 17x8 225/45/17 (5zigen/azenis) street and 17x8.5 255/40/17 (ssr/r888) for track.

 

I realize that "style" is just a personal preference, but in that regard, I think this is a classic example of what alot of people, particularly young ones, don't get:

Just because something is good, it doesn't mean more of it is better. That's how you get front yards full of 50+ lawn ornaments... it all starts with a little bird bath or a ceramic frog, and then pretty soon you get the jockey, and the wagon wheel, the plastic sheep and the chrome ball on a pedestal.

Lowered cars look cool, but there is a point where it's over-lowered, looks silly, and passes a point where the performance is actually diminished. On an FD, that's about 25" at the fender lips.

Big wheels look cool, but at a certain point, they look silly, and performance is diminished. On an FD that's about 18"

I even think a mildly stretched tire looks good. I think that tires should look "comfortable" on the rim, and be towards the lower end of the recommended wheel size. I hate a tire that looks stuffed on. I had 275/40/17's on 9" wheels for a while, and it really bothered me. 275 on a 10 or 11" wheel looks great. 235 or 215 on a 10" wheel looks ridiculous, and is essentially a "waste" of wheel.

I see from the posts above that there's apparently some cultural aspect to ultra-stretched tires that I "don't understand", or "don't get".... apparently the same for massive chromie rims, zero ride height, and ludicrous camber angles.

I guess the thing that I supposedly "don't get" is some notion that more is always better (since there's certainly no rational reason for this stuff). Well, that's what I think YOU don't get. More isn't always more, and good style and taste mean knowing when to say when... so that your car doesn't end up looking like the automotive equivalent of Vanilla Ice. ... like that piece of **** black car in the attached photo above. That looks like the dream car for a 12 year old.

 

As the old saying goes:

Cheap
Light
Strong

Pick any two.....

 

Pro: To some it looks cool, japanese "bozo" style. Skinnier tire is cheaper

Cons: Not as much grip as if you were to run wider tires meant for the rim. Sidewall damage from the road is a greater risk than before since it is now at an angle instead of straight up and down.

 

I'd say RPF1s fit in all three of those categories.

Tire stretching is all a matter of personal preference. Some people like show cars, some people like "go" cars, and some try to do both. Thats why people have one set of bling bling rims, or one set of TE37s (something light and strong), or they have multiple sets of rims and tires for different occasions. I fall in the last group, where I know my 255 stretched on a 10.5" isnt the best performance but it looks good to me, so I also have a set of 17x10" RPF1s with 275s on them.

If you are buying one set of rims then you should be concerned with optimizing and tradeoffs, but the best solution is buy more rims

 

They're about 14lbs for a 15x8, and are the ONLY ones I've found that will fit an FC in that size that aren't heavy steel wheels, drag wheels that can't handle cornering, heavy chrome muscle car wheels, or super expensive custom wheels ($550 shipped for Rotas vs. $2k+ for custom wheels).

How heavy are your wheels?

While the whole light, strong, cheap, pick any two thing is true in the extremes, there is some middle ground to be had, and then there's the RPF1's, which are strong, reasonably priced, and are in fact lighter (often significantly lighter) than most of the traditionally drooled over Volks, Gram Lights, SSR's, etc. Then there's things like the 5Zigen FN01R's which are a bit cheaper, only a bit heavier and still strong.

 

i wouldn't do it just because i mount my own tires and getting the bastards on and off on my machine would be a huge bitch.

 

I used to run the fno1rc's but no more. I was doing a rally in my awd eclipse and took a small jump, both rims on my pass side broke (spokes broke off). I wouldn't trust those wheels ever again. So those are cheap, light, and not strong when pushed to the limit.