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MG ZR ZS ZT Technical - Tyres options

I need to get some tyres for my ZT260
The rubbber disappeared pretty quickly and I would like more of it at the back.

Will a 245/40R18 fit my 225/45R18 rears?
Neil

Neil, your best bet is to go to a tyre company website - Pirelli, Michelin etc. They all have tyre size info / tools. I'm thinking of putting Pirelli P Zero Rosso tyres on my ZT 1.8T, but I'll stick to the original size as I don't have the problem of excessive power that you do! Just a word of warning about mixing different size / types of tyres front and rear: it can upset the handling quite badly. I alway rotate my tyres and replace all four at a time.

Regards,
Mark.
Mister T

Yeah I looked at rotating the tyres but the rears were pretty shot away already, so I've left them on to fry at the back and so I'll just have to replace 2.
The fronts look like new!

Mytyres.com woman said dont get anybigger then 225/45R18s as they'll foul the bodywork....but I am sceptical about this response.

Neil

Fouling of the bodywork usually only occurs on changing the rim size, as a tyre cannot really protrude much beyond the rim width unless it is a serious mismatch for the rim...
Mister T

This month's TotalMG says that the 235/40 18 is the same rolling radius as the 225/45 and doesn't mention fouling the body. Also, as 225 is limited to about 4 manufacturers, the 235/40 is bound to be cheaper.

Martin
Martin ZT

Hmm my calculations make the 235/40s 8 mm smaller

245/40s are better at 6.5mm smaller but do they fit the rims?
Neil

Got this from Rog

My running report on my 260 in the April Enjoying MG included referring to the need to change the rear tyres at 10100 miles, down to the tread wear indicators, perhaps a little into them on the inside edge of the nearside tyre, but mirroring your experience. Richard Monks car has also seen the need for a replacement rear pair of tyres too with a few less miles than mine and most use is with his wife. Then having had time to chat with people at Longbridge and across the road at Sport and Racing seems to indicate that they thought 10k was good! 7 to 8k was referred to as a not uncommon life for rear tyres and double or more for the fronts. Indeed now at nearly 14k I find plenty of life left in the front on mine.

The May issue I report on the driving experience on Dreadnoughts supercharged 260, but in the context of this message I also found some very, very interesting experience with the Toyo Proxes T1R tyres fitted to that car (standard sizes). The ZT135 we went to Scotland in had the standard Continental tyres and I found that the car was less than fully secure on some of the local roads with damp patches. The same roads in the same conditions with the Toyo's with supercharged V8 and traction control off was far better and next to no slip at all. No indication on how long the Toyo's would last bearing in mind that the general rule being more grip - less life!

Further information is that there were several ZT385 development cars running at Longbridge. I am told that they were using standard 18" wheels but fitted with 245/40x18 tyres for a marked improvement in stance and apparently better road grip. Interestingly this is the size to go for to retain gearing and speedo accuracy as the size difference to standard is just 1%.

.......

So I've ordered two 245/40 R 18s
Neil

Good luck Neil, and do give us feedback on the rim fit, fouling etc. I'd be very interested, as my tyres are nearing the end of their useful life too. I hope you don't get too much understeer with fronts narrower than rears. If you have to use power oversteer to get round corners your new tyres may not last too long...

Mark.
Mister T

Neil
Was that 245 all round, ie. front and rear?
What was the price of the 245 like compared to the 225.
Mark, my tyres, too, in the next 5k miles. I reckon 245 would look good even if only a 160 V6!

Martin
Martin ZT

Martin,

You need to visit Jim Jeffrey in Warrington. wwwjeffreyshpt.co.uk. They have much more in stock than what is on their website.

You will never see anyone taking more care to avoid damaging your alloys and their prices are rock bottom.

Andy
Andy

Thanks Andy.

That's worth knowing as I also need some 185/70 14s fitting to my freshly restored Rostyle rims on my BGT.

Also Kwikfit managed to damage my ZT alloys by using a "tyre lever" to remove the centre pieces instead of the speical tool carefully provided in the wheel well!
Martin ZT

ironically 245/40R18s cost less than 225/45R18s as more manufacturers make them

I will report on them one fitted etc

Martin remember ...you cant get thicker than a Kwikfit fitter!

Neil

Hmmm .... interesing. I'm running Avon ZZ3 225/45 18's on my ZT CDTi, and have great grip (even in the wet). No road noise either, and the tread pattern looks great!
P V Moran

This thread was discussed between 09/05/2005 and 13/05/2005

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