15" vs 17" wheels

All,

I prefer the look of the higher profile rubber on the 15" wheels. So I am looking at pros and cons as I understand them at this point. I am hoping that those with experience in comparing 15" vs. 17" setups can offer some guidance and help me to see what I may be missing or where I may be mistaken in my analysis. For context, I am thinking of doing a 351w or 347 stroker for street use only.

Pros

I like the aesthetic
Softer ride

Cons

Choosing 15" means fewer (ane more expensive) tire options.
Limitations on which brakes you can run (for instance, the popular willwood setup is apparently in compatible with 15" wheels.)
It seems that low-profile tires have been widely adopted due to their performance characteristics. Thus, I am assuming that the 15" wheels may not handle as well. This may or may not be an appreciable factor for me.



I have heard that Gordon Levy offers brake packages for 15" wheels. Any other vendors I should look at? Does running the smaller rotors that the 15" rims require make powered brakes more of a necessity?

Thanks for any and all feedback!
Zach

Zach,

I have both 15s and 17s for my car and you've pretty much hit all of the issues with the pros/cons you listed. There are others, but those are the key ones. There are still a few choices for 15" tires out there, but if you want performance, you're going to have go with a vintage race tire - either a bias ply like the Goodyear billboards (sports car specials) or radials like the Avon CR6ZZ (which is what I'm running).

The ride is better on the 15s in my opinion - due in large part to the fatter sidewall - and you don't give up anything in performance if you use the above mentioned tires. However, I did have to go with smaller brakes on the front to fit inside the 15s. I swapped out the 13" Baer (SVT) set-up I had originally and went with the stock GT brakes from FFR.

From an aesthetic standpoint, I'll let you be the judge...

http://i845.photobucket.com/albums/a...ps06eb6c72.jpg

http://i845.photobucket.com/albums/a...psifbp7kd2.jpg

IMO, tires and tire availability are going to be the overriding decision point. The brake situation is quite manageable. There are options, whether OE style or aftermarket like Wilwood that will give good performance for street use. You don't have to go power for this reason alone. Some prefer power (me included) but depends on what brakes you end up going with. Wilwoods for example most would recommend not using power. Ride quality is very subjective. Have you actually ridden in one yet? I've only used 17's in my builds, and I'm actually quite surprised about how good the ride quality is. No matter the tire size, the car has a totally rigid chassis and a stiff suspension. This is going to give a certain ride quality. I don't find it harsh at all. But certainly not your father's Oldsmobile either. Springs, shocks, and suspension choices all play into the ride along with tires. Personally I wouldn't make a decision on this point alone. So in the end it becomes about tires. I've recently been doing some research myself on this, and was really surprised how few options there are. Some sizes look good, but the the treadwear ratings (UTQG) are off the charts for use as a performance tire. May look good, but could be very disappointing in actual use. There are also some choices that are not DOT rated. Guys still drive these, but I personally wouldn't on the street. In my review, the three I found that were possibilities were Hoosier, Mickey Thompson, and Avon. Given where the industry is going with tires sizes (bigger is better...) I can't help but think in the future the possibilities will be even less. Good luck.

Based on the recent announcement from FF, looks like you need to add 18 inch wheels to the decision mix. :rolleyes:

One quick note, don't get too concerned with aspect ratio of the tire, sidewall height is more important. Compare two tires, 315/35/17 vs 285/35/18....both work out to roughly 26" tall. But the sidewall of the 17" tire is about 4" vs 3.5" with the 18 tire. The 17 will give you a fairly nice ride, but as you get into 18's, it starts to get a little stiffer. As far as 15's, it would be hard to find a tire that has a short stiff sidewall, but having had muscle cars for years, it's VERY hard to find performance tires, other than passenger car and race tires. I ended up with 17" tires on my Dart, specifically 295/45/17 drag radials. I really wish FFR would do a slight redesign on their wheelwels to accommodate taller tires, that would open up more options.

One other option is to try 16" rims. There are more tires available and the 'look' is similar to the 15". This is what I did on my '33.

One other idea relative to the brakes is to consider steel wheels in 15" rim size. They may fit over the larger calipers.

Best regards, Tom

I went with 17s after I looked at the "safety" issue. I have no idea if they were correct but when I looked there were a lot more radial tires available in 17 than 15 which was the clincher. I wanted true knockoffs and went with Bob at Vintage. Not cheap but beautiful. They fit fine over my 6 piston fronts and 4 piston rears from Gordon Levy. All in all, at go cart stage, I am pleased. Having said that the knockoffs are somewhat a pita to slop on the anti seize and installation. But look great. Henry

You can easily go with some 4 Piston Wilwoods all around and they will work extremely well...I say go for the look you want...It's your car...With tires, options are minimal but go for it...

Chris,

Thanks for the response. I did those Avons but particularly like the Billboards that you mention.
Definitely prefer the 15" aesthetic - thanks for the side-by-side comparison.
How are the stock GT brakes from FFR working for you?

Zach

edwardb -

Thanks for your reply. Yes, I saw that FFR is now offering the 18' wheels. Being that those are even lower profile, I doubt that I'd consider them.
To answer your question, yes, I have had the opportunity to ride in a roadster with 17" wheels. I did not find the ride quality objectionable in the least - it is what I was expecting. As I mentioned, I am considering the 15" wheels mainly for their aesthetic and only mentioned ride quality for the sake of trying to make my pro/con list more complete.

Thanks again,
Zach

Tom, that's a consideration that I had not even been aware of. Thanks

Henry - Yeah, definitely lean towards the true knock-offs as well.

Christenfreedman - So I hadn't considered that the 4 piston willwoods would fit. I suppose you could but 4 pistons front and back rather than 6 piston front and 4 piston back… Maybe that's a good solution. I had read that the willwood setups from FFR do not work with 15" wheels and just assumed that that applied to the 4 as well as 6 piston brakes.

Thanks for the replies

Quote:

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Originally Posted by ZachT

edwardb - Thanks for your reply. Yes, I saw that FFR is now offering the 18' wheels. Being that those are even lower profile, I doubt that I'd consider them. Thanks again, Zach

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Hopefully you saw my rolling eyes sarcastic smiley. It was a lame attempt at being funny, given the "spirited" discussion right now about the 18 inch wheels. Understand if you're seriously interested in 15 inch for aesthetic reasons, 18's are not on your radar.

Regarding the brakes, having the same, or near the same, brakes front and rear would be a good thing. Most FFRs w/ stock type brakes are really under braked in the rear. The 4 piston front and rear sounds great to me.

Just as an aside when looking at tire sizes. You need to got to a site like Tire Rack that lists the exact physical dimensions of the tires. The standard 255X35X17 is just a starting point since they are not exact measurements. I have had personal experience where sets of Yokohama & Goodyear's were all most an 1" different in tread width, to Yokohama's advantage, despite having the same advertised as 255X35X18's.

Believe the industry standards are gamed by the marketing departments for better numbers in some cases. Physical measurement will also help to prevent the tire from rubbing.

Zach,

The brakes are very good, but about what you'd expect if driving an old car (since mine are non-power). When I first go-karted, I had the SVT 13" brakes on the front, and I actually like the balance of the later model GT brakes on the front with the SVT rears. However, the 6 & 4 piston set-up from Wilwood would be cool if you could get it to fit in the 15" wheels. Possibly something I'd consider upgrading to down the road.

Thanks for the replies, everyone.

I feel so strongly about this... If I can't get 15" tires, I will not build a second car that is in planning stages.
I will run square bill boards before running 17,18,19 wheels and tires. Just my opinion

This is a very interesting thread. I too, really like the aesthetic of the 15's, and I don't think it is a bias because my car has them. I think most of the cars I see with the 17's are stunning as well, it's just, well, the 15's work for me. I plan on billboards when that need arises. Hopefully I can still get them!

I was at a Cars & Coffee last summer, the first time I had taken my own car to one. Another gentleman (perhaps he is a member here) showed up, so it was kind of fun to have these cars parked next to each other. Crazy nice car, superior to mine in every way. But I do remember this - as he was studying mine, he said something to the effect of "I still like the look of the 15's on these."

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