Vovchandr Posted December 1, 2019 Share Posted December 1, 2019 Hello track experts. Trying to narrow down a second set of wheels and or tires options for the 7 for the obvious occasional track day. I'd like to stick to 13's but options are limited and nice options are very expensive. Limited options for tires doesn't help. I have a wide variety of 4x100 15's. They aren't fancy but they will do the best job bang for the buck considering I already have them. Is it a reasonable option to use 15's with an adapter? Does it need to be hub centric? Selection for 15's is much easier isn't it? I think 15's I have now are 0 offset and worst case scenario they won't work either way but I'm certainly at least willing to try/mock them up after getting an adapter. Thanks Link to comment Share on other sites More sharing options...
Vovchandr Posted February 9, 2020 Author Share Posted February 9, 2020 I'm still on the lookout if anybody has advice. Currently window shopping 4x108's in 15s. Although I fear I might run into fitment issues with the front fenders that are made for 13s or have to run a really small tire to fit. Link to comment Share on other sites More sharing options...
JohnCh Posted February 9, 2020 Share Posted February 9, 2020 I'm pretty sure Scannon added hub adapters so he could use his Mata wheels. Might be worth a PM. I have H&R bolt on spacers on the back of my car. Very well made and they do a version that allows you to change PCD called the Trak+ Wheel Adapter. Of course, they may not make an adapter for 4x108 to 4x100 and they will adjust the offset which may or may not work with your existing wheels, but might be worth exploring. -John Link to comment Share on other sites More sharing options...
scannon Posted February 9, 2020 Share Posted February 9, 2020 I took my 2005 SV and an aftermarket Miata 4 X 100mm wheel and tire to an engineering company. They did some measuring and calculated what thickness to make it and what sized the hubcentric flange and relief should be. IIRC the cost was about $200. The adapters had different thicknesses, both were about 1" thick. IIRC I used 205/XX-15 front tires and the rear was 225/XX-15. Link to comment Share on other sites More sharing options...
Croc Posted February 9, 2020 Share Posted February 9, 2020 Vlad - why 15 inch for track? Convention is usually towards 13s unless you have a CSR which makes it difficult for anything but 15s. Are you trying for a specific rubber brand? Link to comment Share on other sites More sharing options...
Vovchandr Posted February 9, 2020 Author Share Posted February 9, 2020 Vlad - why 15 inch for track? Convention is usually towards 13s unless you have a CSR which makes it difficult for anything but 15s. Are you trying for a specific rubber brand? Tire availability and the fact that I could potentially already use 15's I have without having to buy another set of wheels. The marginal downsides of the rotational mass/etc are a non factor for the few (at most) track days I'd do a year. Pretty much trying to have a backup/primary set at minimal cost. It's a high risk situation to be facing during a tire failure but trying to minimize that risk in the most efficient way. I like my SLR 13s and will likely keep them for the street bouncing between badly sized Toyos and hard to source/more costly Avons. Link to comment Share on other sites More sharing options...
Vovchandr Posted February 14, 2020 Author Share Posted February 14, 2020 I took my 2005 SV and an aftermarket Miata 4 X 100mm wheel and tire to an engineering company. They did some measuring and calculated what thickness to make it and what sized the hubcentric flange and relief should be. IIRC the cost was about $200. The adapters had different thicknesses, both were about 1" thick. IIRC I used 205/XX-15 front tires and the rear was 225/XX-15. Thank you. This will be the route I'm likely to pursue regardless since I already have 4x100 wheels. Lets call this plan B. In the meantime I came across a plan A. What appears to be a set of 420R 15in wheels. Will those have trouble fitting under my existing stays? I know Caterham sells two different sets of stays and fenders whether 13 in or 15 in. Link to comment Share on other sites More sharing options...
Croc Posted February 14, 2020 Share Posted February 14, 2020 (edited) Be brave, go for it, try to fit the wheels then discover if you need to buy new stays. :seeya: Being serious for a moment - the diameter of 13s and 15s once rubber is on them was not that different. So maybe work out 15 inch wheel you are going to use - assume you get a spacer like Skip's idea. Spec it with rubber virtually (i.e. dont buy it just yet). Calculate the diameter. Compare that measurement to the diameter of the 13 inch wheel with rubber you have currently and you will know if it works since you know the clearance between your current 13 inch wheel/rubber and the stay and you know the diameter/width differential. Thats how I worked out I could flip from CR500 to Avon ZZR and ZZS on my CSR. Its probably 0.25-0.5 of an inch (or less) greater diameter and no wider as the rubber will taper towards the tread in that extra diameter. Edited February 14, 2020 by Croc Link to comment Share on other sites More sharing options...
Vovchandr Posted August 18, 2020 Author Share Posted August 18, 2020 Realized I never posted an update Got my track day/second set of wheels in and on to test The tire profile is quite different but it seems to work. More of a function over form Sent from my Pixel 3a XL using Tapatalk Link to comment Share on other sites More sharing options...
Vovchandr Posted August 18, 2020 Author Share Posted August 18, 2020 13s for comparison Sent from my Pixel 3a XL using Tapatalk Link to comment Share on other sites More sharing options...
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