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A spec sheet I have for Euro Cups states 225/50 frt, 245/45 rear for street tires, and 245/45 frt, 255/40 rear for racing slicks. I don't recall coming across a 255/40/16 tire ever, and slicks typically do not use that sizing convention.
These days, 245/45s all around is what I did and would run on 8 and 9 x 16 mag PD's.
Hey guys,
Just want to confirm that 225/50 (front) and 245/45 (rear) are the correct spec tire sizes? My mechanic just called and is installing the tires now and was questioning if the size is correct as he thinks the front tires are somewhat narrow for the rim. Appreciate your help!
Was able to get the tires on - thanks for confirming. Definitely need bigger spacers for the front than I currently have on the car. Based on the thread that was recommended, I need 29mm of spacer to match the early offset. That said, I can only find spacers in 25mm or 30mm (hubcentric). 30mm would be slightly wider.
Thoughts on going with the 25mm or 30mm for the front wheels?
I used a set of the mag phone dials for track/racing use for several years, and never had an issue with them. Not common today, but some years ago I knew of at least a few cars that were racing on them consistently and I don't remember hearing of any failures.
They are a mag alloy, not pure mag. I think they are reasonably durable. By comparison, I have cracked BBS E26 cast mag centers.
Nothing I said is to imply they are bullet proof, and with any wheels this old, you don't know the history - how much hard loading (track) use they have seen, how many curbs they have hit, how many walls they have hit, etc. So there is always potential for failure, so be sure to check them thoroughly, and use them with some consideration of their material of construction, age, and current and future collector value.
I was dealing with a Mg/Al alloy, not prure mag. Perhaps the thicker structure of the automotive wheels helps with longevity as compared to bicycle tubing thickness, but it was bad enough in the bicycle tubing to kill the project. The material was also severely prone to corrosion if uncoated or scratched down to the bare substrate. Certainly conditions of use and damage/cycles would come into play for cup wheels.
Was able to get the tires on - thanks for confirming. Definitely need bigger spacers for the front than I currently have on the car. Based on the thread that was recommended, I need 29mm of spacer to match the early offset. That said, I can only find spacers in 25mm or 30mm (hubcentric). 30mm would be slightly wider.
Thoughts on going with the 25mm or 30mm for the front wheels?
Run the 30mm. You're going to be dialing in some negative camber anyway so you should be fine.
Apologies for the delay in following up with pictures. Ended up going with H&R 28mm spacers in the front and rear which is 1mm shorter than matching the late offset. After a test drive she definitely needs an alignment but I’m happy with the look and quality of the spacers.
Last shot is of a cup car which is the look I am aiming for.
Considering that the widest street tire available is a 245, the 9" wheel doesn't get you much except for the "ooh" factor. Personally I wouldn't drive on them without having the paint stripped and the wheels magnaflux'ed (or whatever the equivalent is for magnesium). Especially considering that Cup cars were never driven gingerly.
You also have to monitor them for corrosion. Magnesium corrodes very quickly if left unexposed. It is also very flammable. I think in Japan they have prohibited the use of Mg wheels in the Super GT series.
I would also take care to use only the lugnuts and torque values Porsche and/or ATS specified for this wheel. It looks like they don't have a steel insert, so using a steel lugnut may accelerate wear on the seating area. I don't know how much the painted seat area alters this.
I'm not familiar with Mg Phonedials specifically, but Mg wheels generally require more attention.
They certainly look good though.
Last edited by FrenchToast; 09-05-2018 at 08:34 PM.
FrenchToast, appreciate the feedback. Since these are Magnesium Alloy, I think the flammability and corrosion issues are not as extreme as opposed to an all Mg wheel. I've come across a few other sets of Mg Phone Dials that have been treated very poorly and did not see any corrosion or cracking. At some point I likely will have them refinished and treated/dipped to prevent any corrosion but so far 300+ miles have gone well and with some aggressive corning, I've checked spacers and lug nuts without any backing out.
07-31-2018, 11:17 PM
