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MG MGF Technical - Tyres setup for MGF?

Does anyone know why Rover decided on 185 for the tyres in front and 205 rear for 15 inch tyres and 205 all round for 16 inch tyres?

What would happen with 205 all round on 15 inch tyres?

Thanks,

J



Jay

Jay

They didn't - at first there were only 15 inch wheels the 16 inch option did not come out until much later.

I think that the original set up was for two reasons:-

Non PAS cars would be lighter with narrower tyres and it helped to balance the over/under steer of the car.

Enthusiasts showed MG that they wanted bigger tyres all round so MG decided to offer them.

Ted
Ted Newman

Precisely as Ted suggests: the tyre sizes for the 15" wheels were determined for the best & safest balance. Check out the Lotus Elise- it has a very similar disparity between front and rear tyre sizes. Presumably this is to reduce the amount of grip at the front to get the cars understeering before oversteer catches out the unwarey.

Which raises the sensible question: why do 16" wheel equipped 'Fs have 215/40 R 16s if this differential is so important?

I suspect that the answer to this is expediency. Clearly MG had a tyre supply deal with Goodyear. Therefore when the market demanded larger wheels, MG looked to Goodyear to supply. NCT-3 tyres do no come with 16" fitment sizes- so another tyre from the range had to be choosen- the excellent Goodyear F1. Check out the fitment sizes available: there aren't sizes narrower than 215/40 for 16" rims. Developing new rubber for the 'F clearly wasn't in the budget, so... Yes, you guessed it, 215/40 R16s got fitted to all four corners.

There is very little detriment for doing this (except increased tram-lining)- and mostly lots of gains for the superior tyres- so this for many has been the enthusiasts choice.

Rob
Rob Bell

I have noticed behaviour on my VVC with 16" wheels that I guess is what yo udescribe as tram-lining:

If I am not pointing in a straight line, or the road has a pronounced camber, when I brake I particularly notice that I have to put effort in to steer the car straight. It's not a major problem, but having read bit's about the non-standard tracking setup and wondered if these changes would improve this particular aspect of the handling.

I also read quite a few comments about needing 'compliance washers' if you alter the tracking on the rear wheels. I'm not much of a DIY'er and wondered how much these would cost to have fitted by someone who knows what they are doing. My F is a MY2000, so it came with a 3 year warranty. Does anybody know if these kind of changes (and maybe an air filter that so many people rave about) would be likely to affect the warranty.

Cheers
Nigel Hannam

Nigel or anyone else ...

I have a set of unused compliance washers. Paid 10GBP for them. I did not use them as I have poly bushes now. Any offers ?

Gaz
Gaz

I wanted more Oversteer so I fittes 205x50x15s all round I found the car did more steering than me on uneven or rutted roads, at speed this could get quite dangerous. I then got the polly bushes fitted and this effect was much less but was still there. I now have 195x50x15s on the front I still get less understeer than standard but don't get the car tramlining effect.

Gaz, the compliance washers are not an either or item with the bushes, if you fit the Polly bushes you can still fit the washers. Polly bushes alone do not cure the problem that the compliance washers solve. I had both fitted to my car.
Tony Smith

...But you can get comliance washers with the poly bushes, Andy Gillhooley has this on his F, nice purple bushes & matching washers.

Hmmmmm, purple (_8(I)

SF
Scarlet Fever

Gaz,

I was guessing that the compliance washers would not be too expensive. I was more curious about how much I would be charged to have them fitted (guess I could talk to a mechanic) and if they would reduce the handling features discussed.


If I decide to have the work done, I'd certainly consider buying the washers off you...

.. that's if you still want rid given the above comments.


SF, Is that a Homer Simpson smiley? Not seen it before!!

Nigel
Nigel Hannam

The compliance washers are not too much work as far as I understand it. If you are serious about sorting out the suspension the polly bushes are a must (in addition to the compliance washers. The compliance washers are simply spacers that take up some of the play (polite word for it :-) in the rear supension.

The polly bushes (all round + compliance washers) should take five to six hours labour according to MS (if I remember correctly). I don't know the cost of just the washers but I know it is nowhere near this amount of work. Maybe someone else can tell exactly.

If I was Gaz I would keep the washers and have them fitted also.

Andy, I have black washers with my purple bushes.
Tony Smith

This thread was discussed between 12/01/2001 and 14/01/2001

MG MGF Technical index

This thread is from the archive. The Live MG MGF Technical BBS is active now.