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MG MGF Technical - Cup car wheels

Recently purchased some 16" cup car wheels, been after some for ages, with good rubber left on them. The rears have got contisport 205/50/16 w rating and the front have NCT 5 205/50/16. The fronts are rubbing on the arch lining, which I think is more to do with the fact that my hydrogas needs pumping up, so i'm not worried about it. I'm more concerned about different makes of tyres on different axles and so want to resolve this by putting contisports alround. I've read the archives about tyres etc and lots of info about 215/40's alround for 16" rims and the trophy using 195/45/16 on the front and 215/40 on the rear, even small bit about using 205/50/16 alround for the bridgstones but nothing on whether you can use 205/16 on the rear and then 195/45 on the front. Will this combination work ok. If not what would you reccomend bering in mind that both sets of tyres have at least 7mm of rubber left!
Jack Dillon

Jack,

I believe that this si quite a difficult question to answer as I doubt that anyone has tried 205/50/16 on the rear and 195/45/16 on the front as this is outside the rec. diamateres set by rover. The closest is the trophy F which as you mention has 195/45/16 on the front but 215/40/16 on the back. I'm not knowledgable enought to discuss the exact probalms that you may enbcounter with thinner tyres on the rear other than issues with oversteer/understeer and resultant poor handling. Maybe Rob Bell or SF etc would be able to shed a more learned answer. I would have thought that you would be ok.....but like I say it's really only speculation
Rob

Copied from the general board:
Jack,
The same people tend to read both boards so no need to post on both.
I am not sure if anyone has actually tried 205/16 rear with 195/16 front as most Fs with 16 wheels seem to either have 215 all round or 215 rear and 195 front. But a common size for the 15 inch wheels is 205 rear and 195 front, so that width combination is fine.

The thing that concerns me is the 205 tyres you have are 50 series which would give a much greater diameter than the more normal 215/40x16, 195/45x16, 205/50x15 or 195/50x15.
If you really have 205/50 x16 tyres then you will be raisng the gearing (and increasing speedo inaccuarcy)of a standard F by fitting them.
Jason H
Jason H

I agree with Jason.

Scarlet currently runs 205x45 16 Marangoni Zeta Lineas all round - these have a 6mm greater rolling radius than the 215x40 16s that are normally fitted. In my case this is just about within tolerance (the wear on a tyre tread). If you go for 204x50 16 then your speedo and mileometer are likely to be out of true. No idea by how much, but it is likely to be cumulative, in so far as the faster you go the further out it will be and likewise the more miles you do the further out your trip/mileometer will be - you wouldn't want to do 20K on these tyres and clock up 25K on the mileometer would you? This is probably an exageration, but the principle is the same.

SF
Scarlet Fever

I personally use 215/40s all round - having the same diameter on all four wheels has the advantage that you can even up the tyre wear front to rear by swapping the wheels on the same side.

Andy has good experience with 205 tyres on 16" rims - as has Dave Livingstone (45 section too?)

As for the question on wether it is good to mix 195 and 205 on 16" rims - well I don't foresee this as being a problem - it is certainly a combination that I've used on 15" rims in the past. Nicely balanced combination IMO.

You may struggle to find a tyre manufacturer who sells all these sizes (Goodyear and Bridgestone don't for example - I can't comment on Continentals because I have not tried them) - but if you do, then go for it by all means. But as has already been mentioned - be aware, when using non-standard tyre sizes on the rear wheels, that speedo calibration can be noteably affected.
Rob Bell

> >as has Dave Livingstone (45 section too?)

Yes, 205x45 16" all round for the last three years.
Dave

I was flicking through an old copy of MG world last night, that my old man had passed onto me....basically to throw away, anyway I came across an article on the maidstone sports cup car for the 2001 season (said it was old). They were quoted as using 205/50/16 Dunlop DO1J control tyres on the car. Why would they use this eries of tyre if it would mess with the calibration of the car...wouldn't that be illegal under race rules? Furthermore, the fact that they use this size of tyre on the F would usaggest some advantage over the standard tyre sizes mentioned above. Is it a case of greater tyre daimeter = improved grip? Excuse the lack of knowledge, but i'm hear to learn!
Rob

Rob, could be a combination of several things. The race series will have had a deal with Dunlop which was attractive to competitors - but possibly Dunlop only had appropriate tyres for racing in 50 section at that time. Also when a control tyre is used then any change to gearing will affect everyone the same so there is no advantage so it doesn't matter.
David

That would make perfect sense....thanks David.
Rob

If you fancy a set for track days, I believe that Brown and Gammons sell them :o)

The 16" 'Cup wheels on my car were originally from an MGF Cup racer - and had a set of these tyres on them. Sadly, the vendor removed them when I went to collect them - I'd have dearly loved to have found out exactly how much better these tyres are on the track over road tyres :o)
Rob Bell

This thread was discussed between 06/10/2003 and 07/10/2003

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