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RUnning bigger tyres on the 17" 225 rims

2K views 16 replies 3 participants last post by  David Shearer 
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#1 ·
As we are a little behind the times in OZ, the std 225's only came with 17" wheels. These were running 225/45/17 profile tyres. All the perfrmance commodores and falcons here run 235/45/17, hence there is a lot of variants of these tyres around and they're a lot cheaper than 225/45/17. I was just wondering, given the width of the wheel (6.5"), could I run a 235 profile tyre without too much trouble?

I'm thinking of running the Dunlop SP Sport Maxx or the Good Year Eagle F1

Cheers
Dave
 
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#3 ·
cactusbob said:
Correct me if I'm wrong someone, but I think the facelifts over here run 225/40 R18 without the cup pack, and 235/40 R18 with the cup pack. Apart from the colour the wheels I think are the same so you may be OK
thanks for that.

Are all the 18" wheels 7" though? If they're 6.5" then I'm fine, but not too sure
 
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#5 ·
andy bassett said:
yes mate the cup alloys are wider so they run a 235 on the 8" wheel, but you can run a 235 on a standard 7.5" alloy, many are doing that now over here for better handling and traction.

and the dunnys on mine are the dogs, alot better than them shat contis
Cheers for that, yeah I reckon the dunlops would be a great improvement over the contis. Saying that, i've managed to get 34000 kms out of them so far with a few mm left in the indicators.
 
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#6 ·
David,

Replacing the existing 225/45/17 with a 235/45/17, you will change your speedo accuracy by 4.4%. Thus, your speedo will read 4.4% slower than actual (assuming that it is spot on at the moment. Who knows?)

Mimimum, Maximum & Optimum wheel widths for a given width tyre are also affected by the aspect ratio of the tyre. Running a 235/45 on a 7.5 inch width wheel should be OK. You should not, however, run a 235/40 on a wheel width less than 8.0 inches.

The reason that 235/45/17 prices are so much lower than 225/45/17 in Australia is because the 235/45/17 is the volume seller. It is the size for past model Commodore SS and Falcon XR6/XR8. Until recently, not that many cars required came ex-factory with 225/45/17.

Your factory 17s are a 6.5 inch width are they? I thought they were a touch wider. More like 7.0 or 7.5?
 
#7 ·
BlueyZarzov said:
David,

Replacing the existing 225/45/17 with a 235/45/17, you will change your speedo accuracy by 4.4%. Thus, your speedo will read 4.4% slower than actual (assuming that it is spot on at the moment. Who knows?)

Mimimum, Maximum & Optimum wheel widths for a given width tyre are also affected by the aspect ratio of the tyre. Running a 235/45 on a 7.5 inch width wheel should be OK. You should not, however, run a 235/40 on a wheel width less than 8.0 inches.

The reason that 235/45/17 prices are so much lower than 225/45/17 in Australia is because the 235/45/17 is the volume seller. It is the size for past model Commodore SS and Falcon XR6/XR8. Until recently, not that many cars required came ex-factory with 225/45/17.

Your factory 17s are a 6.5 inch width are they? I thought they were a touch wider. More like 7.0 or 7.5?
4.4% :lol: :lol: :lol: wow

and they are 7.5" and the cup ones are 8"
 
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#8 ·
BlueyZarzov said:
David,

Replacing the existing 225/45/17 with a 235/45/17, you will change your speedo accuracy by 4.4%. Thus, your speedo will read 4.4% slower than actual (assuming that it is spot on at the moment. Who knows?)

Mimimum, Maximum & Optimum wheel widths for a given width tyre are also affected by the aspect ratio of the tyre. Running a 235/45 on a 7.5 inch width wheel should be OK. You should not, however, run a 235/40 on a wheel width less than 8.0 inches.

The reason that 235/45/17 prices are so much lower than 225/45/17 in Australia is because the 235/45/17 is the volume seller. It is the size for past model Commodore SS and Falcon XR6/XR8. Until recently, not that many cars required came ex-factory with 225/45/17.

Your factory 17s are a 6.5 inch width are they? I thought they were a touch wider. More like 7.0 or 7.5?
Geez 4.4% is a fair bit and its already not spot on. I guess it would have to depend on how much I'd be saving on tyres if I went to a 235 size.

I got 6.5" off the spec sheet on drive.com.au. Probably not the most reputable site for renaults. :lol: I'm glad they are 7.5" though, well I hope they are.
 
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#12 ·
cactusbob said:
How will wider tyres but the same radius wheel and profile affect your speedo accuracy? Surely they are just wider, they don't have a bigger diameter
225/45/17 -> 235/45/17

We are not talking about changing the radius of the wheel. We are talking about increasing the diameter of the tyre. A 235/45 tyre has a taller sidewall than a 225/45 tyre. Therefore the overall tyre diameter is larger.

The main thrust of the post was regarding the suitability of running a 235 width tyre on a 6.5" wheel. But David (and Andy Bassett) corrected this by stating that the 17" diameter wheels are 7.5" wide, not the 6.5" that David had got from a website that knows bugger all.

The upshot is that changing from a 225/45/17 to a 235/45/17 is OK on a 17*7.5 wheel if you are prepared to accept the change in speedo accuracy.

David, you might be surprised as to how much cheaper the 235/45/17 is than the 225/45/17. In some cases, it can be over the $100, depending on make/model. I assume that the Eagle F1 is the GS-D3 model that interests you. This is available in both 225/45/17 & 235/45/17. Not sure that the Dunlop SP Sport Maxx is available in 225/45/17, so may not be able to get a price differential for that one. I'll contact my brother in the business for some figures.
 
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#13 ·
David Shearer said:
As we are a little behind the times in OZ, the std 225's only came with 17" wheels. These were running 225/45/17 profile tyres. All the perfrmance commodores and falcons here run 235/45/17, hence there is a lot of variants of these tyres around and they're a lot cheaper than 225/45/17. I was just wondering, given the width of the wheel (6.5"), could I run a 235 profile tyre without too much trouble?

I'm thinking of running the Dunlop SP Sport Maxx or the Good Year Eagle F1

Cheers
Dave
Dave,

If you look on the frame of the drivers door, there is a tyre placard. It's right near where the door catch is. The rims are 7 inches wide on our cars. Not only are we short changed on the diameter of the rims but the width too!

I've been looking at tyres as well. You can get 225/45 17's in the Sport Maxx Dunlops for the Megane. I'm convinced they're the best you can get after reading a few reviews. Check this review out:

http://www.tirerack.com/tires/tires.jsp?tireMake=Dunlop&tireModel=SP+Sport+Maxx

Check all the other tyres as well - I think the dunlop comes out the best.

I only have one concern. Apparently the only Sport Maxx we can get in Oz for the megane has a load rating of 94 (the standard tyre has a load rating of 91). This means that the sidewall of the tyre is stiffer because it's been designed to support the weight of a heavier car. It won't be as springy and hence it will have some effect on the ride. Not sure how much though. Anyone else change their tyres and replaced them with a tyre that has a higher load rating? What are they like?
 
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#15 ·
JamieMac said:
Yeah I have changed to both higher and lower load ratings and it doesnt seem to make any difference at all, I have just changed to Dunlop Sport SP 9000 and all I can say is WOW, as Andy will agree that my full fat is handling like gold!!!
Thanks for the response mate....I'll be getting the Dunlops without a doubt...
 
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#17 ·
JoeA said:
David Shearer said:
As we are a little behind the times in OZ, the std 225's only came with 17" wheels. These were running 225/45/17 profile tyres. All the perfrmance commodores and falcons here run 235/45/17, hence there is a lot of variants of these tyres around and they're a lot cheaper than 225/45/17. I was just wondering, given the width of the wheel (6.5"), could I run a 235 profile tyre without too much trouble?

I'm thinking of running the Dunlop SP Sport Maxx or the Good Year Eagle F1

Cheers
Dave
Dave,

If you look on the frame of the drivers door, there is a tyre placard. It's right near where the door catch is. The rims are 7 inches wide on our cars. Not only are we short changed on the diameter of the rims but the width too!

I've been looking at tyres as well. You can get 225/45 17's in the Sport Maxx Dunlops for the Megane. I'm convinced they're the best you can get after reading a few reviews. Check this review out:

http://www.tirerack.com/tires/tires.jsp?tireMake=Dunlop&tireModel=SP+Sport+Maxx

Check all the other tyres as well - I think the dunlop comes out the best.

I only have one concern. Apparently the only Sport Maxx we can get in Oz for the megane has a load rating of 94 (the standard tyre has a load rating of 91). This means that the sidewall of the tyre is stiffer because it's been designed to support the weight of a heavier car. It won't be as springy and hence it will have some effect on the ride. Not sure how much though. Anyone else change their tyres and replaced them with a tyre that has a higher load rating? What are they like?
Cheers guys,

Yep, I think I'll probably go the dunlops, really liked them feel of them on the cup when I drove it so its probably worht the adjustment in the speedo for me! Just got to check the price now!
 
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