Going from stock 18s to 16s - going lightweight

8592 Views 37 Replies 10 Participants Last post by mumixam, May 6, 2017

mumixam

Discussion Starter · Apr 28, 2017

Philosophy behind the choices is strong and lightweight. I am looking for improved performance and comfort with the change. Looks come in last but i do like the look of bigger sidewalls and the oz wheels. I have a white m3 s-touring model for reference.

https://www.tirerack.com/wheels/Whe...h=Black+Painted&showRear=no&packageFlow=false

OZ Ultraleggara black 16x7 45mm offset - 14.7 lbs which isnt the lightest on tirerack but close. From what i know OZ makes some pretty high quality / strong wheels, the Kosei is lighter but the offset tucks it in more and i have read a few stories about them cracking under normal use. The RPF1s im not a fan of the look/ color available.

Was thinking of matching them to a set of 215/55r16 conti dws tires - they are 21 lbs and i think i would like to keep the same tirewidth. 205/60s dont seem to have as great of tire choices. They are slightly smaller diameter - 1.2% shorter gearing with the change, 69.2 mph actual at 70 indicated - doesnt seem bad to me. Looks like they will fit fine, not sure if scrub will be affected.

Was also thinking of picking up the Koni FSDs at the same time, or maybe slightly after to improve comfort a bit more - wasnt thinking about changing springs at all though, stock ride height is fine by me. Not sure if there is a spring setup more comfort focused - stock seems like it might be the way to go.

Feel free to leave a comment- im interested to hear thoughts or maybe other combinations i haven't thought of, i really have only been browsing tire rack because its easy and they will mount/balance for free and ship to me quickly.

-mum

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arathol

· #2 · Apr 28, 2017

17x7.5" rims are a good compromise. You can find light 17" rims fairly easily and somewhat inexpensively. Tralkites, Advanti and Konig are good ones to look at. The 7.5" Traklites are just a bit over 15 lbs each. Look at wheels for the 3rd generation Miata, 2006-2015 for a wider selection. Check out Goodwin Racing for more choices.

Better tires sizes are available for 17" rims too. 205/50s on 7.5" rims is a good choice for performance.

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arathol

· #4 · Apr 28, 2017 (Edited)

mumixam said:
The traklite gear 17x7.5 45mm wheels seem pretty nice - 200 with free shipping on ebay is nice and 15.5lbs - not a fan of the other styles for them.

im looking through the other brands now

Is there a reason you recommend a wider wheel than stock and a narrower tire? Im still learning this stuff but that doesnt seem like a logical choice. Unless its just to open up good options to choose from?

You need to look at tire specs and actual pictures of various combinations to get a feel for how various tires fit. Not all tires are the same. Tread width can vary considerably from tire to tire. Performance tires can be significantly larger than standard all season type tires in the same size.
For example -

Both are 205 width. Continental ECS 205/50-17s on the left, Dunlop Signature HP 205/60-16s on the right.

As for tire/wheel choice, you can actually get more grip that way. A 205 on a 7.5" rim will stretch the sidewalls just slightly, enough to make the tire a bit stiffer and more resistant to rolling the sidewalls under in a corner. This will generally keep the tread face on the road better than a wider tire with a sidewall that rolls. You'll also see quicker steering response due to less sidewall flex.
Unless you buy a true sports car, OEM tires are usually selected for appearance and according to manufacturer recommendations more than to maximize performance. The market wants tires that have square shoulders with vertical sidewalls and perfectly flat tread face because it looks cool, so that is what you get. There are almost always better wheel / tire combinations that make the car handle better.
The Conti DWS is a good tire, but its not a real performance tire. It has real soft sidewalls, not great for ripping up a canyon or autoxing, but they ride well and are pretty good in the wet. A better choice would be the Michelin PSS or the new Conti ECS if you want a summer performance tire, or the Michelin Pilot A/S 3+ or BFG Sport Comp2 A/S if you want a year round use tire.

The Conti ECS tires on 17x7.5" Traklites -

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arathol

· #7 · Apr 28, 2017

Stewie said:
Why'd you want go to lighter?

Lighter is always better. Less unsprung weight is a good thing.

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arathol

· #11 · Apr 29, 2017

mumixam said:
I cant recall what the stock 16 alloy setup weighs, i think the steelies are like 24 lbs or something tho, i can definately see 18s coming in under both

what 18s are you looking at?

Just for future reference, the 18" OEM rim/tire weighs in at just over 50 lbs. The steelies w/tire is ~44 lbs, the 16" alloys are ~40 lbs w/tire. OEM Mazda 6 19" rim w/tire is something like 53 lbs.:surprise:

18" rims are not lighter than 16" rims, not by a long shot. You can get 18" rims that weigh in at about 17 lbs but they are near $400 a wheel and up for good ones. Lighter rims are available at ridiculous cost, in the thousands.

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arathol

· #16 · May 1, 2017

minsanity said:
There are affordable 18s out there that are as light as pricey 1s....
Genuine 57Xtreme 18x8.5 et45 weighs 9.2kg each

A cheaper & lighter option....Rota Titan 18x8.5 et44

There are 3 options when it comes to choosing wheels.
Light, strong and cheap. Pick two, that's all you get.

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arathol

· #23 · May 2, 2017

Midnightsky228 said:
For the sake of curiosity, why not a 225/50? More potential lateral grip correct? Or is the downside to that the requirement of an 8 inch wide rim? Or could you fit a 225 on a 7.5inch rim?

A 225 will work no problem. It depends on how big the tire actually is physically. The 205 in the pictured is more like some 215 tires.
It is quite possible to get more grip from a 205 as opposed to a 225 on the same rim. Read the posts on the first page of this thread. The sidewalls of a 225 on a 7.5 inch rim will be nearly vertical or have an outward taper, allowing the tire to roll under the rim. A 205 will have a bit of a stretch so will be stiffer.

Lanesky said:
I really want 17 RPF1's in sbc and I was wondering this as well. Glad to see someone posting a pic with 17's and I assume a semi stock height. Gives me hope that my car off the stock 18's wont look silly. I like the beefy sidewall look.

My car is lowered on H&R springs, 45mm R and 30mm F. 205/50s on a 7.5" rim using factory springs will probably open up that so-called "wheel gap" about a half inch or more depending on the tire. 225/50s will be a bit larger than OEM.

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arathol

· #29 · May 3, 2017

Midnightsky228 said:
Yup that's the one, I want maximum grip for a street tire simply for Autocross. Beyond that I have been told it has been an excellent tire sold under Bridgestone in other countries already. Wet grip was excellent and dry grip was excellent, so I definitely want a set.

Its a Bridgestone RE003. However there are better tires out there. If you want the best autox tire, the Bridgestone RE 71R should be at the top of the list. Dunlop Direzza ZII Starspecs are close behind. The new Hankook Ventus RS4 is said to be very good too. Yokohamas Advan Neova AD08Rs are pretty close also.

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arathol

· #32 · May 3, 2017

dradernh said:
This an example of a light, strong wheel: BimmerWorld TE:AL TA16 Forged Race Wheel - 17"

How much do they actually weigh? I have noticed that many vendors don't or won't post weight.

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arathol

· #34 · May 3, 2017

johnzcarz said:
I didn't read through all the responses, but one thing I want to point out is that you are going to get better ride quality out of the 16's (or 17's) than you would for an 18" tire. I actually went through this on an ATS. The one I bought had factory optional 18" rims. I was OK with it on the test drive but after living with it through 1 winter (and our Northeastern pot holes) I dreaded driving the thing. So I went with an aftermarket 17 and conventional tire (vs. the run flats). The change in ride was night and day. I know your M3 doesn't have RF's, but the more sidewall you have the less harsh the ride. The penalty is slightly less responsive steering - the extra flex in the sidewall that helps absorb road imperfections also absorbs some of the steering 'feel'. The good news is I bet 99% of people wouldn't be able to tell the difference.

This ↑ ↑ ↑

And if you are worried about steering response, there are tires with stiffer sidewalls to restore that too.

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arathol

· #37 · May 5, 2017

Here is a good alternative in grey

Konig "Hypergram" 17x8 Matte Grey for MX5, 17x8

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