Limitations with 15" wheels?

[ZachT]

Hi All,

I have a question regarding 15" wheels on the roadster. I like the look but understand that there are certain limitations that one must accept in choosing to go with the 15" wheels. Specifically, I understand that you can't order the Wilwood upgrade from factory five if you decide to go with the 15"
wheels. I have also heard that the new IRS requires some modifications to work with 15" wheels.(Please correct me where I may be incorrect in these assumptions)
When I do a build I will probably be well served to keep things as straightforward as possible. Thus while I understand that there are probably workarounds which would allow me to have IRS and Wilwoods with 15" wheels it would probably be best for me to go with 17" wheels instead if running 15s necessitates too much added complexity.

Thanks,
Zach

[Gordon Levy]

I have part that will work for you. I have Wilwood kits for 15" wheel and a kit for the 2016 IRS system

[ZachT]

Gordon, thanks for the response. what does the IRS kit involve in terms of installation/modification of the 2016 IRS?

[CraigS]

Use the search button. There have been several threads covering this.

[edwardb]

This is one build thread where Gordon's Wilwood setup was used in the newer IRS with 15 inch wheels. http://thefactoryfiveforum.com/showt...5-quot-wheels).

My understanding is the IRS setup itself isn't changed, but does require special brackets from Gordon to allow the brake caliper to fit inside the wheels. The other issues are the ebrake and then finding suitable 15-inch tires. I'm not sure how this fits into your "keep things as straightforward as possible" build goal. But it's certainly possible.

[Duke]

Looks like photobucket screwed over my thread. Lovely. I'll have to find a new hosting site and update the thread at some point. PM me or right click on the pictures and open directly in photobucket and you 'should' be able to see them.

15's are a little more expense, but Gordon developed a very solid solution that gives track worthy brake performance, allows you to use the '15 IRS, and solves the ebrake problem for any state registration. Some states require a manual hand brake, others you can get away with a line lock valve to lock the rear brakes on the existing brake system. Call Gordon and talk through it, he's a great source of knowledge. Not sure what state you are in, but others here may be able to ID what your requirements are faster than google.

For me, getting the correct look with the 15" wheels filling out the wheel wells was critical for my goals while maintaining 10/10 performance on the street and track. For the best 15" tire, Avon is your best choice on the market.

[CobraboyDR]

I have part that will work for you. I have Wilwood kits for 15" wheel and a kit for the 2016 IRS system

Gordon, does your 15" solution for IRS allow for pin drive wheels?

[wareaglescott]

Just a thought on your concern of adding any complexity to the build from someone who just completed their first build and had essentially zero automotive experience going into it. Going into the build I also shyed away from some items I thought would add complexity. As I got into the build I found you learn so much and gain so much confidence that task you deemed very difficult going into the build becomes very manageable. If you want the 15" wheels just go for it. The forum is a great resource for figuring any issue out and you can do it. Build this thing just how you want it. You can get through any complexity and looking back you will be glad you did and may be surprised at what you are able to accomplish. I know I was.

[edwardb]

Gordon, does your 15" solution for IRS allow for pin drive wheels?

You would need shorter upper/lower control arms, CV axles, etc. to allow the suspension to still work with the added length of the pin drive adapters. These parts come from Factory Five as part of the newer IRS option. They have stated they are not supporting pin drive with this IRS setup.

[Gordon Levy]

Yes, they will fit pin drive

[ZachT]

Thanks to everyone for the helpful comments. Can anyone with experience comment on the handling and ride qualities of 15" vs 17" wheels?

[ZachT]

Paul - thank you for the link!

[ZachT]

Just a thought on your concern of adding any complexity to the build from someone who just completed their first build and had essentially zero automotive experience going into it. Going into the build I also shyed away from some items I thought would add complexity. As I got into the build I found you learn so much and gain so much confidence that task you deemed very difficult going into the build becomes very manageable. If you want the 15" wheels just go for it. The forum is a great resource for figuring any issue out and you can do it. Build this thing just how you want it. You can get through any complexity and looking back you will be glad you did and may be surprised at what you are able to accomplish. I know I was.

Thanks for the words of encouragement. Your build has been inspirational to follow. hope you're enjoying the product

[ZachT]

Looks like photobucket screwed over my thread. Lovely. I'll have to find a new hosting site and update the thread at some point. PM me or right click on the pictures and open directly in photobucket and you 'should' be able to see them.

15's are a little more expense, but Gordon developed a very solid solution that gives track worthy brake performance, allows you to use the '15 IRS, and solves the ebrake problem for any state registration. Some states require a manual hand brake, others you can get away with a line lock valve to lock the rear brakes on the existing brake system. Call Gordon and talk through it, he's a great source of knowledge. Not sure what state you are in, but others here may be able to ID what your requirements are faster than google.

For me, getting the correct look with the 15" wheels filling out the wheel wells was critical for my goals while maintaining 10/10 performance on the street and track. For the best 15" tire, Avon is your best choice on the market.

great information! I am currently in Hawaii but will have moved on by the time I do start a build. I'm a dentist in the Army and get restationed every 2-3 yrs. Thabks for the recommendation on the Avons - I had been eyeballing those already.

[GoDadGo]

Something To Think About:

While 15" wheels Look Great, it does put you in a situation where most of your available tire selections will only carry an "S" Speed Rating which is only 112 MPH.

I'm running 245/45-17's up front and 285/40-17's out back in an attempt to hide the fact that I've got 17's on my MK-4.

https://youtu.be/BcsVu80VG5k

[ZachT]

Something To Think About:

While 15" wheels Look Great, it does put you in a situation where most of your available tire selections will only carry an "S" Speed Rating which is only 112 MPH.

I'm running 245/45-17's up front and 285/40-17's out back in an attempt to hide the fact that I've got 17's on my MK-4.

https://youtu.be/BcsVu80VG5k

I did not know that. I'll have to see whether that applies to the Avons. Thanks for the heads up

[Gordon Levy]

Avon are high speed rated tires. The other thing to consider is speed rating are done on 3400lb production cars, not 2300lb roadsters.

[GoDadGo]

Avon are high speed rated tires. The other thing to consider is speed rating are done on 3400lb production cars, not 2300lb roadsters.

Gordon,

I know that Avon has a good reputation for two-wheeler tires and that's great news about them having speed rated 15" for our cars, but where can they be purchased?
I checked Tire Rack, Discount Tire Direct and some other internet vendors since the retail tire shops near my home don't sell Avon tires.
Can you suggest a reputable vendor along with the tire model number, please?
Thanks-N-Advance!

Steve

Note: I'm smelling an additional set of rims getting ordered if the tires aren't a hassle to purchase.

[CraigS]

Avons can be bought here
http://rogerkrausracing.com/

[KDubU]

Steve,

Craig has noted Kraus Racing on the West coast. There is another on the East coast, name is escaping me at the moment. Kraus will get them to you quickly though.

Edited to add I have Gordon's Wilwood package for 15's and they work great.

[Gumball]

I originally planned on 17s for my car, but ended up with 15s due to the period-look that I moved closer to during my build. I drove it as a go-kart for a couple hundred miles (my hobby shop is at a fairly large municipal airport with lots of access roads) and then for a short time on the street with the 17s. But, for the past two summers - and for a couple months so far this summer - I've driven it on Avon CR6ZZ tires, which are basically a DOT radial race tire with a vintage tread pattern.

The ride is a little harsher with the 17s, due primarily to the low sidewalls - also, there was more tram lining due to the fact that I was running 315s in the rear and 245s up front. Although you can't call the suspension on one of these "compliant" in the way that term is applied to modern cars, it is somewhat more comfortable with the 15s - at least in my opinion.

In addition to Kraus, the other authorized Avon reseller in the US is http://www.sascosports.com/

Also, depending on your build, the 15s may just look better than the more modern rubber with larger wheels......

[GoDadGo]

Chris,

Thanks for posting your car with both sets of rubber on it
It gives us all a great Apples-2-Apples Comparison!

Steve

[ZachT]

I originally planned on 17s for my car, but ended up with 15s due to the period-look that I moved closer to during my build. I drove it as a go-kart for a couple hundred miles (my hobby shop is at a fairly large municipal airport with lots of access roads) and then for a short time on the street with the 17s. But, for the past two summers - and for a couple months so far this summer - I've driven it on Avon CR6ZZ tires, which are basically a DOT radial race tire with a vintage tread pattern.

The ride is a little harsher with the 17s, due primarily to the low sidewalls - also, there was more tram lining due to the fact that I was running 315s in the rear and 245s up front. Although you can't call the suspension on one of these "compliant" in the way that term is applied to modern cars, it is somewhat more comfortable with the 15s - at least in my opinion.

In addition to Kraus, the other authorized Avon reseller in the US is http://www.sascosports.com/

Also, depending on your build, the 15s may just look better than the more modern rubber with larger wheels......

great side by side shots!

[CobraboyDR]

IMO, the 15's definitely look better on a vintage sled...

[Mountain-Metalworks]

I have 15" Halibrands from FFR and Gordon's Wilwood brakes for these wheels. One extra thing worth mentioning for later on down the road, when you get the tires balanced pay special attention to where they put the tape weights. I mounted my rear tires after balancing and the first hand spin with the tires off the ground knocked the weights off and scratched the cr@p out of my brand new Wilwood calipers. Not a huge deal since you can't really see the scratches, but I'll need to get the tires re-balanced.
Front weights were in the same place but just clear the calipers.

-TJ

[JBMorrison]

Chris,

What sizes are you running front/rear with you 15" ?

[Gumball]

Chris,

What sizes are you running front/rear with you 15" ?

225s front and 245s rear. The Avons have a pretty generous cross section, so although the numbers would make you think they're pretty skinny, they actually have a good contact patch, plus they look much more period correct than the 275s that I originally bought for the rears (and was going to use the 245s on the front).