lets talk wheel weight
 

if you have any relevant threads feel free to link them, i read the forum a lot.

im going to be getting 18x10.5's

this is inherently going to be a heavier wheel than 17x9's. with that in mind, id like to not get something TOO heavy. that said, what do you think is average for a 18x10.5?

i can get a set at 29lb/per @$700/set
https://www.fitmentindustries.com/bu...568-18x105-20?

i can also get a set at 23lb/per @$1600
https://www.maperformance.com/produc...12105121890374

the pf01 is part of enkeis "racing" line, the line with rpf1, nt03, rs05rr, so its considered light, but 23 lbs still seems heavy

i emailed fitment ind. and they sourced both these weights for me
id prefer not to get cheap wheels, but dont know if 6lbs justifies double the price. thoughts?

This doesn’t compute. You want 10.5” wheels but are worried about the weight? Get over it. Even if you fork out big bucks for forged wheels they are still gonna be heavy.

Enkei RPF-1 17 x 8 5 x 100 +45 = 16lb

You dont get RPF-1 in 18 x 10.5 5 x 100 but the 5 x 114.3 are 19lb.

I am curious about your rim size, a 10.5" rim fits a 295 (A052),

You running a boosted LS?

:cheers:

Last week I changed wheels/tires to a combo that saved 5 lbs/wheel.

Can I feel the difference? Yes, but honestly it is subtle, not dramatic. IMHO wheel weight is a bit overblown unless you are seriously racing. I doubt this would be worth double the cost...

FWIW I went from 23 lb 18 inch wheels to 15 lb 17 inch wheels... substantial wheel weight savings but offset by heavier tires.

The main reason I switched was to go from offset wheels to square wheels so I can rotate tires; I like to slide the rear daily!

Get what you like most, weight shouldn't really matter unless you're competing.

If you are willing to go with a 9.5 width, Konig Dekagrams look similar to the XXR wheels you linked and they weight 19.8lbs (slightly lighter than stock). You can go up to 255 width with 18x9.5 but tires are going to be extremely expensive compared to 17".

https://konigwheels.com/wheels/flow-...eels/dekagram/

If you have upgraded to BBK, email Konig with the template and they will let you know if it fits.

yeah Konig has some light wheels for the price

^^^ What they said. If you are really looking for cheap, big rims, that are fairly strong (flow formed), and are light weight, Konig will be one of your best bets. I did research for months to find wheels for a good price at a good weight, and I settled on the Hypergrams. Only thing is, at your size, they often don't come in your offset. But the Hypergrams for example, at 18x10.5, hang under 20 lbs. And if you find the right place to buy them, you can probably snag them for around 200 a piece. Just a quick search and I found Discount Tire offers them for 212.

I asked this question to my good friend and team race engineer recently. My goal was to prove a 18x9.5 inch wheel with a 265/35 200tw tire is faster than a 17x9 with a 255/40 200tw tire despite the weight increase 5.75 lbs per wheel and .3" taller diameter. My theory is more tire = lower lap times. A 255 is the widest 200tw tire for a 17" wheel. Switching to 18's opens up a whole new world of tire widths. But is the weight and height worth it? This was his reply.

"As expected, the larger/heavier wheel/tire combo required more energy to cause an acceleration. However, since you're increasing both size AND weight, you kind of get double dinged so i was surprised by how much. angular momentum is increased by weight and size, and angular velocity is increased by size. Between the size and weight increase, the proposed tire/wheel combo will require roughly 7% more energy to accelerate, assuming an average speed of 91 mph at watkins glen. At tracks with a lower average speed, this effect will be less noticeable (the reciprocal goes for tracks with higher average speeds). Next I'll calculate changes to stopping capacity. I won't be able to calculate for the increase in thermal capacity (This won't affect outright speed anyway, but it will affect consistency) or the affect size will have on adhesion, so the assessment will be done strictly with regard to changes in overall friction forces. This will still be a good point of comparison though as the adhesion forces will increase marginally (yes, you're gaining contact patch, but you're loosing some temperature)."

Okay, now i've calculated the theoretical difference in lateral speed and have equated that to lap times. I found a study that was conducted to see how tires deflect under load and how that equates to contact patch (and more importantly, contact patch pressure). I made the assumption that your tires will react similarly, so I was able to simply scale their data based on your tire size increase. The interesting thing is that size and performance don't seem to track linearly. in this case, a 6% increase in size only equates to an effective 0.9% increase in cornering speed. Based on an assumed average corner speed at watkins glen and assuming you're using all available grip, this should equate to roughly a 0.7 mph increase in average cornering speed. This increase in speed will reduce lap times by roughly 0.4 seconds. The additional speed you carry down the straights will also be of benefit. I've assumed an average straight line speed increase of 0.5 mph (the taller tire will effectively reduce the car's mechanical advantage, which means it will be slightly more affected by drag and hills), which should yield 0.5 seconds. In total (and ignoring the effective torque loss from the larger/heavier wheels), you should be down 0.9 seconds over your old setup. It's really difficult to estimate how the torque loss will effect lap times, but i'm guessing at this point the larger wheel/tire package will still be an advantage (though it might not be 0.9 seconds in reality).

it's definitely a good, functioning theory. I didn't get a chance to look at braking, but I'm guessing that's going to be another few tenths. I'm not sure how much the larger/heavier wheels will affect lap times, but my guess is that's also going to be a few tenths. Let's say you've got -0.9 tenths for the turns, -0.4 tenths for braking, and maybe 0.4 tenths for the weight/size increase, you're still going to be down almost a second a lap. It's really hard to say exactly how much time the new setup will take off due to the heavily nuanced nature of the governing physics at play here, but it'll definitely be faster (my estimates as to how much faster are speculative and shouldn't be treated as gospel).


I realize this is more of a track based analysis but here we see that extra weight does not mean slower as long as it is met with more tire. I will do my best to answer questions about this but please don't ask too many. It is WAY over my head. I can attach his calculations if you really want. Hopefully this helps.

I feel like I should add that the wheels I was comparing are MUCH lighter than the ones you listed though. 29 lbs per wheel is a lot!!!

my take away is that the rpf1, a very light wheel, is 19lb for 18x10.5, so a wheel weighing 23lb would be considered average for the 18x10.5's.

but also, im hearing a lot of: dont actually worry about weight too much, a) im not seriously competing and b) if wider a wheel is met with more tire, its a fair compromise

18x10 527F XXR are 20.2 lbs each. They have a 5x100 (only) bolt pattern and are +40 offset.

+1 Konigs...

I currently have 18x9 Konig oversteer wheels that weigh almost exactly the same.

I would NEVER consider 29lbs wheels. For our cars. (got them on my truck, lol)

Hmm. I have a hard time speaking in non-track related terms. lol. If it looks good to you than go for it.

You should match your wheel width to your tire width, and your tire width to your power levels / traction needs also factoring in vehicle weight and tire pressure as increasing width doesn't always increase contact patch and will inherently increase weight unnecessarily with no benefit, as well as increase time needed to heat up the tires, possibly even never reaching adequate temps especially if the power level isn't there.

Once you know this choose the lightest weight wheels that fit that criteria that you can afford. Lighter is always better, but overall traction is generally more important.