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MG MGF Technical - 225's on the back -Problem?

Hi when i got my F last year it was fitted with 225's on the back and 215's on the front, all Yokohama's, now ive been looking at new rubber but one company said it was wrong to put 225's on the back and they should be 215's now was he quoting some kind of book for this?? the car handles great wet and dry, does anyone else have the same set up on thier F (16 inch rims )
or am I risking some sort of blow out ?? btw I have done 6 K on this set up and i dont know how old the tyres where when i got the Car
Cheers in advance for your help........ Jon
Jon (NSE 81V)

Jon

He could have been quoting from the MGR Owners Handbook that went out with every car; AFAIK no model was ever specified wider than 215.

Do you have the Owners Handboog? If not I would suggest getting one from a dealer. Are you F MPi or VVC or Trophy?
JohnP

I have an F MPi and my handbook says "no other arrangements are recomended" but they seem fine to me !
Jon (NSE 81V)

225 are non standard. Blokey is probably stating that it's "non-standard" as opposed to "wrong".

Assuming the 16" rims will take a 225 (I'm assuming that that's the case as the last tyre was fitted to it!) then I see no problem continuing with that.

Didn't think that the 'F had enough power to need 225s <grin> but then again I'm more than happy (and fast) on my 15" rims!!
If you like the setup, I see no reason not to stick with it.

P.
Paul Nothard

Didn't Fabrice look into getting 225s for his F? Should be some info on this in the archives.

I agree with Paul - if you've had 225s before, and were happy with them, and want to continue using them, then I don't see any reason why not to replace the existing tyres with tyres the same size.
Rob Bell

Anyone know what the correct profile would need to be to aviod speedo problems?

At a guess say 225x35?

SF
Scarlet Fever

I think 225/40 would be closer to 215/40 than 225/35?
Sidewall heights;
225/40=90
215/40=86
205/45=92.25
225/35=78.75
Kingsley

205/50/15 = 293
225/40/16 = 293.2

0.07% difference, ie spot on.
paul weatherill

Are the standard 16" rims ok for 225s?
Kingsley

well thats what my 225's are on, the multi spoke 16 (MG after sales ones) and they are 225/40 but i have never driven another F so i cant realy tell the difference ! however i have a test track 600m from my house and when i got the car took it through its paces in both wet and dry conditions and was suitably impressed ;-))
as long as im in no danger of high speed blowouts i will continue using 225's back and 215's front
All the best..... Jon
Jon (NSE 81V)

The standard set up is 23 inch diameter wheel and tyre.
the following applies to different set ups:

185/55 15 = 23.01 inches
205/55 15 = 23.07

195/45 16 = 22.90
215/40 16 = 22.77
225/40 16 = 23.08

The 225/40 16 is therefore closest to original set up but all would only have minimal effect on speedo acccuracy.

However, the recommended size is 215/40 16 on the rear, is the 225 reaching the extremes of the safe limit for the rim size?
Chris

>>However, the recommended size is 215/40 16 on the rear, is the 225 reaching the extremes of the safe limit for the rim size? <<

The tyre manufacturer will probably be able to provide that sort of information; frequently find width/profile data on their websites along with recommended wheel widths.

You'll probably find that 225s are recommended for 7.5 or 8J wheels...
Rob Bell

What are the 16" ones on the F 7?
Kingsley

More worrying IMO are the 215mm at the front.
The only MGF that came with that setup was the Brooklands/Abingdon SE (215mm all around, correct me if I am wrong).

Even the Trophy and the TF 160 are going for 195mm.
Erik

F's were supplied with 215s at the front depending on availability of other sizes, i don't think there was any ryme or reason.
Kingsley

>>The only MGF that came with that setup was the Brooklands/Abingdon SE (215mm all around, correct me if I am wrong).<<

No cause for concern Erik - all MGF's fitted with 16" 7J wheels were shod with 215/40 rubber - with the *exception* of the Trophy 160 :o)
Rob Bell

When I was having my Trophy suspension upgraded at Tech-speed they said 225 on the back was the way to to go with 205 on the front!
Blue Pocket Rocket

Kinglsey,

15 inch 5, 6 and 8 spokes are 6.0
16 inch 6 spokes are 7.0
16 inch Minilites are 7.0
16 inch Trophy are 7J
16 inch lightweight are 7J


Chris

Sorry, I missed this thread !

Yes, I have 225/40-16 on the back for 2 years now, and I am on my second set (now Dunlop SP 9000's).
On the front, I have 205/45-16.
I'm happy with this combination. I chose it because it's the same diameter than OEM 15" setup, and because I could get G-Y F1 (GSD2) in those dimensions both front & rear. Now I think the GSD3 are not (yet ?) available in 225/40-16... but I'll soon get a set of them for the front.

The grip is great, but that's less fun than 205&195/50 on 15" wheels. There's maybe a bit too much understeer, but then you'd get exactly the same with 215 & 195 combination.
BTW, we are talking about a difference of only 10 mm , and you'd be surprised to measure tyres of different brands and of the the same "official" size !
I have not checked, bit I'm almost sure that 225 is not the maximum width for 7J wheels. They would more than probably even accept 235's.

HTH,

Fabrice
Fabrice

The maximum tyre width for 7J wheels depends on the profile of the tyre. Most tyre manufacturers will allow 225 tyres to be installed on 7J rims, but only if the profile is at least 45. 225/40 tyres will require 7,5J rims, whereas 225/45 tyres are allowed on 7J rims.

If you think about it, it does make sense since the edges/sides of such a wide tyre will need to be pressed inwards to fit, and a taller 45 section tyre will have more give and be more flexible in this respect than a super short and super stiff 40 section.

This, of course, does not mean that it is impossible to fit a 225/40 tyre onto a 7J rim, as Fabrice's experience shows, but it is outside most tyre manufacturers' recommendations.

Per
Per

This thread was discussed between 09/04/2003 and 10/04/2003

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