advantage/disadvantaqe of rim width

What would be the advantage of an 18x8 over an 18x7.5? Seems like they both fit most of the same tires?

wider rim means you can put on a wider tire, a wider tire means more rubber on the road, more rubber on the road better traction

wider rim means you can put on a wider tire, a wider tire means more rubber on the road, more rubber on the road better traction

 

 

Very true:lol: I guess I should have better phrased the question. I understand wider is better for traction, but as a daily driver is that extra 1/2" even going to be noticable or is this more of a concern for track guys.

Might make for better steering feel/sharper response depending on the tire type/size.

 

The 7" wide stock rim is not a bad choice for the smallish to begin with re92's but they aren't exactly the 1st choice for replacement tires for most people around here.

To properly answer the question, you'd really need to tell us what size tire you plan on running.

 

If you are assuming the same size tire for both rim widths, than the rim width that's better matched is what you'd want.

 

If you are assuming optimum tire width for the rim width, then obviously the wider rim and tire will give you better traction.

even as a daily driver they come in handy for rainy days, accident avoidance, or for gravel/dirt roads. But if your an agressive daily driver, then you will enjoy having the extra traction

So is there any disadvantage to running a wider setup?

So is there any disadvantage to running a wider setup?

 

cost.

 

wider rims and wider tires generally are slightly more expensive than their narrower counterparts.

tires and rims are more expensive, plus you may need to fine tune your alignment. more if your lowered

Worse gas mileage with wider tires.

 

Bigger contact patch = more friction between your tires and the road = more resistance = a harder working engine.

 

Although for all intents and purposes, you won't notice a difference.

When I went with wider wheels (17 x 8) on my IS300..the steering tended to pull on uneven road surfaces. I always assumed it was due to the wider rim and tire.

When I went with wider wheels (17 x 8) on my IS300..the steering tended to pull on uneven road surfaces. I always assumed it was due to the wider rim and tire.

 

With wider tires your car will be more susceptible to that feeling of getting sucked in to ruts and imperfections in the road.

^i think that has more to do with the tire on the rim rather than the width of the rim in particular.

No doubt lower profile tires with stiff as hell sidewalls make this worse. Rim/tire experts care to chime in?

wider wheel, offset, tire size, tire compound, and alignment, sus setting will

all affect the handling characteristics of a car.

 

simple 8 and 7.5 difference, you will be able to better fit wider tires on the

wheel, or the same tires with a slightly stretched sidewall increasing steering

feedback. it can (may) introduce tramlining as well. more contact patch does

not necessarily mean better traction, it depends on the tire compound and

design, etc. etc.

Bigger contact patch = more friction between your tires and the road = more resistance = a harder working engine.

 

Does the contact patch really get bigger, or does it just change shape? I can see how it would get get wider, and shorter from front-to-back, but I thought the actual size of the contact patch would be a function of tire pressure, not tire width. (Assuming you run the same air pressure, of course.)

all posted above is true, i went from a 225/60/14 on my celica to a 245/45/16.....oh god wow, so i can take corners like no other but tire prices are insane, for falkens anyway

Does the contact patch really get bigger, or does it just change shape? I can see how it would get get wider, and shorter from front-to-back, but I thought the actual size of the contact patch would be a function of tire pressure, not tire width. (Assuming you run the same air pressure, of course.)

 

yes, very minor, there's a given point to where you dont want to over-stretch a tire to where you are using the sidewalls as part of your contact patch. You are squaring up the tire by going with a wider rim.. so the shoulders of the tires are now touching the ground whereas a narrow rim will round out the shoulders.

 

And yes, your sectional width will get wider as well for sure.

Wider wheels/tires are all above plus

 

heavier

more rotational inertia

worse in inclement weather (rain, snow)

 

Krzys

I think the only things that change the surface area of your contact patch are vehicle weight and tire pressure. Changing tire size only changes the shape of the contact patch. Generically, increasing only the tire diameter will change the shape such that the contact patch is longer north->south which improves braking. A wider tire changes it so that it is longer east->west for more lateral grip.

 

Someone feel free to correct me if I'm wrong on the above.

I think the only things that change the surface area of your contact patch are vehicle weight and tire pressure. Changing tire size only changes the shape of the contact patch. Generically, increasing only the tire diameter will change the shape such that the contact patch is longer north->south which improves braking. A wider tire changes it so that it is longer east->west for more lateral grip.

 

Someone feel free to correct me if I'm wrong on the above.

 

 

not quite.. you have to remember that this is all realative to the lbs/in^2 you put the tires through. A larger tire diameter (with all things equal) is really hard to calculate without an actual ink footprint made. Heck, we have tread blocks and voids to calculate as well if you really want to get picky. We simply can't generalize it by just vechicle weight and tire pressures alone. Some tires have a large tire pressure operating range (to keep things stable by using more steel plys) to keep the shape of the tire 'acceptable' and 'predictable'.

 

Tire compound type is also a huge difference that you simply can't make it that black and white saying that a wider tire going to generate more lateral grip (suspension geometry plays an important role to that). Depending on your driving conditions and situations, some times we can't say that a wider tire is going to do better/produce more grip and g-forces in the rain than a narrower tire. We have to take in consideration of the surface area and the contact patch's pressure per square inch to find out when the car will hydroplane. Can the wider tire sipe out enough water and fast enough compared to the narrower tire where the water has less distance to be siped out as well as a smaller area for the water to build up under? And how about running in the rain where most of the norm for tarmac racers dial down the tire pressures? There's that part of the science where we are purposely softening the entire suspension rather than making it all harder so that we are not slapping the tire surface on top of the water... we are trying to be soft enough to where the water can be squeezed out and away from the contact patch rather than slapping onto it (think of it as doing a belly flop vs. olympic perfect '10' water entry dive).

 

 

 

Just to keep things very simple to this topic:

 

While using the same tire size:

+ wider rim will help support the sidewall and minimize some of the deflection

 

+ increase in steering response

 

- curb rash is more likely to happen since the face of the rim is closer to being flush or exposed past the tire's sidewall surface.

 

-possible additional unsprung weight needed

 

 

Remember, you could think of this not from the rim width stand point, but what if you decided to pick a particular rim width but you want to go with a narrower tire or a wider tire? Some food for thought. You may want to run a particular tire size, but there's two things that could happen and either you stretched the narrow tire on a wide rim or that you crammed the big tire on a narrow rim. That in itself is a problem as well depending on how agressive you drive or what your needs are. I personally like to have my wheels and tires squared up so that it's more well rounded for any needed use. Some people like to cram wide tires to get more sidewall flex for off-road use, while some like to have the stretched tire for either drifting or show use so that they can have a rounded shoulder to clear fenders and minimize and deflection or slack for high level of road/steering feedback.

 

 

Ultimately from a performance aspect, theres really 2 things you should need to know why a narrow rim and tire would be beneficial:

 

If your conditions need more surface area, you could get a larger tire and use part of the sidewall to help get you out of the mud (I believe that's the norm for Jeep rock climbers).

 

If your conditions need more pressure per square inch of contact pach (such as ice or snow), you would run a narrow tire and rim to have some weight to dig down and into the ice. It's all inversely proportional since the weight of your car and the amount of forces and momentum you create through driving isn't going to increase anymore from a 'perfectly' hard surface.

Keefe, I've got two sets of wheels. 18x8 with Yokohama AS EV100s in 225/40 and 17x8 wheels w/ Kuhmo ASX in 235/40. The Yokohamas tramline much more than the Kuhmos (softer sidewall, more give since a hypothetically wider tire). But wheels are +48 offset vs the +55 offset of the stock 7" wide wheels with the 215/45 RE92s, and both tramline where I never saw noticeable tramlining with the stock setup. Does offset affect how the wheels/tires tramline? Or width? Tire characteristics (sidewall, tread pattern, etc)? All of the above?

^ i've had some instances that others tell me that the car tramlines less.. I havent personally noticed that myself because of the tracks and the streets I run on there arent any really deep grooves that the car ends up following in the lane... I think this part varies based on the street, not so much about the width setup. If you put all the cars on a super flat "perfect" road, then there shouldnt be any tramming.. I think it's all isolated based on the roads you drive on. If you drive 10 different cars on that same bumpy road, all of the bumps should transmit to the suspension.. same goes for tramming. If all 10 cars tram, it's cuz the road is that particular. As to how much? Well, that depends on how grooved and how wide the grooves are on that road and how 'wavy' it is.

good article on tramlining:

http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=47

Thanks for the link. It was a good article. All the variables I named and more!