Minilites; size advice please

[abowie]

So I've inherited a set of splined centre inserts designed to be fitted to an alloy wheel.

I thought I might get a set of Minilite style alloys made for use on track and motorkhanas etc. The main straight at our local racetrack, https://www.thebend.com.au/ is long and I could easily get to 120mph in my E on it.

With this in mind, what should I look at with regard to width and diameter, given that I can choose? I really don't know much about wheel and tyre choices at all.

I was wondering whether going to a 16" or 17" wheel and using a lower profile tyre might be advantageous. I'm going to be limited to a 205 width tyre I expect, but would a 55 profile 17" be better than a 65 or 70 profile 15"?

What do you lot think?

[PeterCrespin]

Presumably if you’re starting with a width in mind (and I’d agree with 205) then you can resolve the profile percentage that it constitutes for your 15 & 16 in tyre choices and appropriate rolling radii? A site like Tire Rack has all the numbers you need.

I have 15x6J bolt-on Minilites on my S2 and had them on my S3. Love ‘em. Can’t tell you the offset, am in Antwerp this week.

[abowie]

Many thanks Peter. Good to hear they are good on the car.

If I'm going to do 200km/hr plus (and to be honest I'm not actually sure I want to) I really want the best traction I can get.

I wanted to know how much a lower profile tyre with the same OD as the original wheels would decrease lateral roll on the tyres on hard cornering and whether going for a bigger wheel would offer a stiffer side wall.

[PeterCrespin]

I would think traction is a given, even on 185s, but you’d want directional stability. I learned a lesson about contact patches the hard way by fitting Jag 18x8” Pentas to my X300. With stiff low-profile 245s the contact patch was much wider than the 16x7” wheels but the car felt nervous on rough straights. For very high speed, I’d seriously consider trying for a long narrow stiff front tyre contact. E.G. pumping up a 185 to, say, 45 psi.

Slight nose-down attitude helps too.

Magnesium Minilites are the only wheels on any car that I immediately noticed a ride difference due to unsprung mass. I switched my S3 OTS from steel wheels (already lighter thsn wires) and hadn’t gone more than half a mile before I noticed a stretch of rippled asphalt was no longer jiggling the car because the lighter wheels were following the contours much better. I’ve still got that set..

The problem I have with splined versions is that the spinners stick out a bit. Remind me of James Bond’s Aston Martin rotating bodywork ripperd

[Jaglex]

For me simple 205/70 VR 15 Vredesteins on 6.5" MWS wire wheels worked very good on the Autobahn up to ca. 220 kph. It's not that they turned bad at higher speeds, but I didn't get to higher speeds for times long enough to judge it. But cruising over the Autobahn is different from racing. So this probably doesn't mean to much for your needs. Anyway the E-Type gets pretty light at higher speed...