For sure the Kart theory is not comparable really because the tubalur frame is the suspension (chassis flex) and it has no diff like the car....but I was using this as an example that the principle must be similar:
that when the wheels are moved outwards, which is what would happen with a lower number offset say ET45 the angle of the dangle changes and under cornering this loads the tyre differently, exactly what I don't know? ........but I bet if you did a track day on a set of et60 oe wheels and then you fitted a set of aftermarket et45 you would encounter more understeer, which is exactly what happen's when you move the Kart wheel outwards.
The Kart rear tyre does not "slide" to get around a corner, this is circuit racing not rally!.......Any scrubbing or sliding in circuit racing is not cool.........it might look good but it's not the quickest way to lap. Hence why the kart chassis flexes and lifts that inside rear wheel off the floor , the 3 wheels allows the outer turning rear wheel to form an arc all on it's own width without fighting with the other rear 8" wide sticky slick tyre.
If only cars were like Karts for chassis tuning it was be so easy..............the front , rear, and side bumpers are all create chassis rigidity. They are bolted with an M6 Bolt and a nyloc nut, You simply slacken off the nyloc a bit, which allows a little bit more flex and this softens the chassis like a coil spring change !!! I had to teach my father how the Kart chassis works which was interesting as he was an F1 technician from 1968 - 1978 mostly with BRM, he couldn't quite believe how basic and crude it was to be effectively tightening and loosening a few bolts which on the track would and could improve a lap time by seconds and be the difference between winning and losing!!
Back on Thread................I do also think any changes will do something it's just what? and if jo bloggs or even an experienced driver would notice a difference.
I think any change below et 50 would not be advisable, et50 and above a difference of (10mm) I don't think would cause too much of a problem ? it may be quite acceptable in daily driving and as you mentioned previously there is a tolerance margin on tyre size, and tread. There must also be some percent of tolerance for the wheel offset that could be used.
Their is always somebody that wants the “Carlos Fandago” look and this is something we at thewheelrestorer come across every day! We can only advise to the best we can, and if a person wants to take the risk it's up to them to accept the consequences..
I would also say for some people: "the point of buying a Lotus in the first place" is because they like the look of it............
My car has been sat outside my workshop now for 6 weeks waiting to get through an MOT, and I've had several people say "Ohh I like the look of that", some have no idea what it is, or how old it is, or the engine size, or where the engine is??? not to mention the handling traits..........
I bought it on spec that it has a reputation of handling well, all be it a little too well and boring ?? but this is also said about the 944 Porsche, which is a well balanced car with superb 50/50 weight distribution, but I like this type of engineering .....not a chassis that oversteers or understeers like a pig !!
I'm not too fussed about what it looks like, I'm still mad for a reliant Robin turned 180 degrees, with a Yamaha R1 engine in the back driving the rear wheel......seriously this will happen sometime. The guy in question is very clever and has fitted a Yam R1 Engine to a MG Midget and is in the process of also putting one in a original Mini.......
I also know too well "a lot of people that buy/sell aftermarket wheels and tyres and have a very limited understanding about just what they are doing"
ciao.
