Bent Rim…stronger and lighter rims? I need advice

[Schmidt]

Well, I have my first bent rim and I’ve come to learn that the rims seem to get beat up and bent pretty easily on the stinger. I’m wondering what you guys do. Is it worth getting new rims for increased durability or stronger rims? I don’t even know where to begin with brands or different types of metals or whatever.

 

[Ohiocruiser]

Go with flow forged wheels. Lighter and stronger than cast wheels, for the "same" price.

 

[Volfy]

Lighter, yes. Stronger usually means heavier, unless you spend some beaucoup bucks on forged. Even then, if there isn't enough tire sidewall, sooner or later a big enough pothole will dent/crack it regardless.

Everybody likes the looks of 19's and even 20's. I don't. Anything larger diameter than what can fit over the brake calipers is extra weight and rotational inertia that hurt performance and risk damage. What works right... looks right. Not the other way around.

 

[Schmidt]

How much would I expect to pay for forged wheels? Do you guys know of any good manufactures off the top your head? Any suggestions?

 

[Schmidt]

Oh I see one thought is to go with the flow forged wheels. I did come across as I was googling last night, which actually is what prompted me to drop a question in the forum.

 

[Volfy]

Technically speaking, there is no such thing as "flow forged" wheel. It's a misnomer term used by some marketeers to make it sound more impressive than it really it. The correct term is "Flow Formed", which can be lighter weight than cast wheels and have stronger barrels (the ourter rim of the wheel). The wheel center, however, is still a cast wheel. Flow formed wheels can be excellent performers for the money and often don't cost much more than cast wheels. I've got two sets of Enkei TFR 18x8.5 and they are right at about 20 lbs per wheel. Forged wheels might save me another 2-3 lbs at most but cost at least twice as much, if not a whole lot more.

See here for the difference between cast, flow formed, and forged wheels: The Strength Difference Between Cast, Flow Formed and Forged Wheels

I prefer established mfrs like Enkei and O.Z. Racing that have been around a long time and haven't sold out their brand names. They make OEM wheels for car mfrs as well as for the aftermarket.

 

[Ohiocruiser]

Technically speaking, there is no such thing as "flow forged" wheel. It's a misnomer term used by some marketeers to make it sound more impressive than it really it. The correct term is "Flow Formed", which can be lighter weight than cast wheels and have stronger barrels (the ourter rim of the wheel). The wheel center, however, is still a cast wheel. Flow formed wheels can be excellent performers for the money and often don't cost much more than cast wheels. I've got two sets of Enkei TFR 18x8.5 and they are right at about 20 lbs per wheel. Forged wheels might save me another 2-3 lbs at most but cost at least twice as much, if not a whole lot more.

See here for the difference between cast, flow formed, and forged wheels: The Strength Difference Between Cast, Flow Formed and Forged Wheels

I prefer established mfrs like Enkei and O.Z. Racing that have been around a long time and haven't sold out their brand names. They make OEM wheels for car mfrs as well as for the aftermarket.

Exactly the ones i have. Price/pound ratio is awsome and look great on stinger.

 

[Stiletto]

Everybody likes the looks of 19's and even 20's. I don't. Anything larger diameter than what can fit over the brake calipers is extra weight and rotational inertia that hurt performance and risk damage. What works right... looks right. Not the other way around.

I agree, if the 18" rims are significantly lighter (5+ lbs). But, 20" rim that has the same weight as an 18" rim will have a very minor rotational mass benefit...less than three pounds if my calculations are correct. In totality, sure, that's possibly 10 pounds less of static weight. But, when talking about a 4000# GT car, it won't make a huge difference in daily or spirited driving.

 

[turboAWD]

I agree, if the 18" rims are significantly lighter (5+ lbs). But, 20" rim that has the same weight as an 18" rim will have a very minor rotational mass benefit...less than three pounds if my calculations are correct. In totality, sure, that's possibly 10 pounds less of static weight. But, when talking about a 4000# GT car, it won't make a huge difference in daily or spirited driving.

Sure, but all things being equal (and they never are), 18" with larger sidewall is less likely to bend a rim when hitting a pothole than a rubber band on a 20".

 

[Stiletto]

Sure, but all things being equal (and they never are), 18" with larger sidewall is less likely to bend a rim when hitting a pothole than a rubber band on a 20".

Depends on the tire. Several extreme summer and track/street tires have very stiff sidewalls.

 

[Volfy]

I agree, if the 18" rims are significantly lighter (5+ lbs). But, 20" rim that has the same weight as an 18" rim will have a very minor rotational mass benefit...less than three pounds if my calculations are correct. In totality, sure, that's possibly 10 pounds less of static weight. But, when talking about a 4000# GT car, it won't make a huge difference in daily or spirited driving.

Problem with that equivalent assumption is that an 18" wheel and a 20" wheel built in the exact same manner and the same load rating will NOT weight the same. There is no escaping physics that the barrel of the 20" wheel will be larger and therefore require more material to construct, ultimately leading to more weight. Look up any line of wheels and check out their weight in different diameter but same width, and you'll find that inevitably the larger the diameter, the heavier they are.

For a 20" wheel to have the exactly same weight and load rating as an 18", it will have to be built with a more rigorous process, possibly forged. That means more $$$.

We can argue hypotheticals all day long, but unfortunately we don't drive hypothetical cars. Physics conspires with mfg cost to favor the smaller diameter wheel - in performance and in cost.

 

[Volfy]

Depends on the tire. Several extreme summer and track/street tires have very stiff sidewalls.

But Those stiff sidewall comes with penalties:

1. Weight. again rears its ugly head. There is just no way around this. More load handling out of less sidewall height means more materials and reinforcements. Look up any of the more popular performance tires and you'll see this for yourself. All else being equal, lower profile (less sidewall) will invariably carry a lower load rating, meaning their cannot sustain the same load as a higher profile tire of the same series/dia/width. And... when you do find another tire that does have an equivalent load rating as the higher profile tire, it will be heavier.

2. Reduce tire compliance. A 20" tire on a Stinger will have to be ultra low profile in order to maintain the same rolling diameter as an 18" tire. This means 255/30R20 vs. 255/40R18. When a tire has that little sidewall - and having to be ultra stiff to carry the same load rating - it simply will not flex at all. While this might not be a big deal on a billiard table smooth race track, most of us drive on roads that are far less forgiving. Over rough pavement and over larger undulations, a tire needs a certain amount of compliance in order to stay adhered to the road surface and to maintain grip. Too stiff a sidewall and too little compliance will simply make the tire bound off the pavement and lose contact/grip. The best tire compound in the world ain't gonna do you much good when it is in the air.

Also, some compliance is necessary for optimum accel and braking. Most folks familiar with drag racing know this.

3. NVH. Short stiff sidewalls will transmit more NVH up the wheel, thru the suspension and into the cabin. That means more road noise. That also means your suspension will be more stressed and have to work harder to dampen the additional movement that would have been otherwise absorbed by a more compliant tire.

4. Road hazards. This brings us inexorably back to the topic of this thread. There is no escaping the fact that your 20" rim - with a 255/30R20 tire - is sitting some 2" off the pavement. Now imagine that wheel/tire hitting a pothole. Even at modest speed of say 60mph, that awfully small "crumple zone" will have a tough time absorbing that impact, before the suspension has a chance to react. Little surprise that Stinger/G70 forums and FB pages are constantly littered with folks posting their dented/crack rims.

 

[Stiletto]

Problem with that equivalent assumption is that an 18" wheel and a 20" wheel built in the exact same manner and the same load rating will NOT weight the same. There is no escaping physics that the barrel of the 20" wheel will be larger and therefore require more material to construct, ultimately leading to more weight. Look up any line of wheels and check out their weight in different diameter but same width, and you'll find that inevitably the larger the diameter, the heavier they are.

For a 20" wheel to have the exactly same weight and load rating as an 18", it will have to be built with a more rigorous process, possibly forged. That means more $$$.

We can argue hypotheticals all day long, but unfortunately we don't drive hypothetical cars. Physics conspires with mfg cost to favor the smaller diameter wheel - in performance and in cost.

Note that I did not mention cost. Of course you would need to exchange materials to be lighter to go bigger. That does not negate my point.

 

[Stiletto]

But Those stiff sidewall comes with penalties:

1. Weight. again rears its ugly head. There is just no way around this. More load handling out of less sidewall height means more materials and reinforcements. Look up any of the more popular performance tires and you'll see this for yourself. All else being equal, lower profile (less sidewall) will invariably carry a lower load rating, meaning their cannot sustain the same load as a higher profile tire of the same series/dia/width. And... when you do find another tire that does have an equivalent load rating as the higher profile tire, it will be heavier.

2. Reduce tire compliance. A 20" tire on a Stinger will have to be ultra low profile in order to maintain the same rolling diameter as an 18" tire. This means 255/30R20 vs. 255/40R18. When a tire has that little sidewall - and having to be ultra stiff to carry the same load rating - it simply will not flex at all. While this might not be a big deal on a billiard table smooth race track, most of us drive on roads that are far less forgiving. Over rough pavement and over larger undulations, a tire needs a certain amount of compliance in order to stay adhered to the road surface and to maintain grip. Too stiff a sidewall and too little compliance will simply make the tire bound off the pavement and lose contact/grip. The best tire compound in the world ain't gonna do you much good when it is in the air.

Also, some compliance is necessary for optimum accel and braking. Most folks familiar with drag racing know this.

3. NVH (Noise, Vibration, and Harshness). Short stiff sidewalls will transmit more NVH (Noise, Vibration, and Harshness) up the wheel, thru the suspension and into the cabin. That means more road noise. That also means your suspension will be more stressed and have to work harder to dampen the additional movement that would have been otherwise absorbed by a more compliant tire.

4. Road hazards. This brings us inexorably back to the topic of this thread. There is no escaping the fact that your 20" rim - with a 255/30R20 tire - is sitting some 2" off the pavement. Now imagine that wheel/tire hitting a pothole. Even at modest speed of say 60mph, that awfully small "crumple zone" will have a tough time absorbing that impact, before the suspension has a chance to react. Little surprise that Stinger/G70 forums and FB pages are constantly littered with folks posting their dented/crack rims.

Never said they didn't have trade offs. Yet again, the fact remains, you can obtain resilient rubber with a lower sidewall.

 

[Volfy]

Note that I did not mention cost. Of course you would need to exchange materials to be lighter to go bigger. That does not negate my point.

Nor did I dispute your hypothetical. I simply pointed out you left out some rather important practical considerations in order to make your equivalence assumption sound more relevant than it really is.

Some folks might not care about cost, but OP certainly expressed concern regarding cost. Relevance is important.

Never said they didn't have trade offs. Yet again, the fact remains, you can obtain resilient rubber with a lower sidewall.

...and you'll be robbing Peter to pay Paul. More resilient = more compliant = even less rim protection, with such low profile tire. That is wholly contrary to the topic of this thread. Again... relevance.

 

[Stiletto]

Nor did I dispute your hypothetical. I simply pointed out you left out some rather important practical considerations in order to make your equivalence assumption sound more relevant than it really is.

Some folks might not care about cost, but OP certainly expressed concern regarding cost. Relevance is important.


...and you'll be robbing Peter to pay Paul. More resilient = more compliant = even less rim protection, with such low profile tire. That is wholly contrary to the topic of this thread. Again... relevance.

Note that I wasn't responding to the OP.

Practicality is relative. It may not be practical for you to fly first class on every flight, whereas it might be practical for me to fly on private jets.

Define low profile tire.

Lastly, go re-read the first post. Nothing about cost is mentioned. Forged rims are pretty difficult to bend unless you're driving like a madman through deep potholes (then again, I've seen bent 16" steel rims with a 275/70 tire on a Jeep). So, if the point of the thread to discuss resilient rims, well, they don't get more durable than forged...which cost more money, yes.

 

[Volfy]

Note that I wasn't responding to the OP.

Practicality is relative. It may not be practical for you to fly first class on every flight, whereas it might be practical for me to fly on private jets.

Define low profile tire.

Lastly, go re-read the first post. Nothing about cost is mentioned. Forged rims are pretty difficult to bend unless you're driving like a madman through deep potholes (then again, I've seen bent 16" steel rims with a 275/70 tire on a Jeep). So, if the point of the thread to discuss resilient rims, well, they don't get more durable than forged...which cost more money, yes.

I think you made your point perfectly clear.

 

[Submarines]

It's the load rating of the wheel you really need to pay attention to; higher load rated wheels will have a thicker rim/lip (usually heavier) that will stand up to pot hole better.

I've bent a set of 18's and 19's (both flow formed) over a year, but my second set of 19's (with higher load rating) has been great before I sold them.

Flow form doesn't mean stronger, it just means lighter; they're engineered to the same strength rating with a thinner barrel relative to standard cast, the overall stress it sees during impact is the same.

The stinger's suspension travel is pretty short combined with a 4000lb load, any pothole will destroy your wheel regardless of diameter. The car needs to be either 400lbs lighter or a higher tire aspect ratio.

My personal set I've engineered myself to have a higher load rating and thicker lip edge to handle pot holes better, the caveat though is if the wheel doesn't bend, then a control arm will.

 

[Ohiocruiser]

My personal set I've engineered myself to have a higher load rating and thicker lip edge to handle pot holes better, the caveat though is if the wheel doesn't bend, then a control arm will.

What do you mean by that? Are you making the wheels??

 

[Volfy]

Lighter-weight wheels means less unsprung mass, which allows the suspension to react faster to road undulations. The Enkei 18x8.5 TFR wheels I have are 20 lbs. That is 10 lbs lighter than the OEM 18x8 that came with my Stinger. 14 lbs (F) and 14.5 lbs (R) lighter than the OEM 19x8 and 19x8.5 that came with our Genesis G70. 30-42% are some very significant weight reduction.

The heavier the unsprung mass, the more it wants to stay exactly where it is - when it hits a pothole - the more likely your tire sidewall will not have enough compliance to keep the rim from a hard strike, before the suspension can react and move the whole wheel/tire assembly up and away.

The lighter the weight, the quicker the whole unsprung mass will move. Combine that with smaller diameter wheels and more tire sidewall is your best chance to avoid wheel damage.

Stronger isn't going to save you from bent/cracked rims. The OEM wheels are heavy precisely because they are overbuilt to be tougher. Peruse through Stinger/G70 forums to see how many bent/cranked OEM rims there are.

If the rim makes a hard strike, damage is just about guaranteed. Relative strength of the wheel only varies the severity of the damage.