Going up a tyre profile size

[capitano]

Hi all, my wife managed to kerb my left side A5 Cab alloys today -last time she gets the car

Now looking at repairs to two badly chewed wheels - but worse still, in the process she managed to tear into the rear tyre. I had intended to update the two fronts very soon but the backs were still pretty good - until now. its on 20" alloys running P Zero 265 30 20's. Question was - as I now must change the fronts and one rear - would I be able to run P Zero 265 35 20's without issue? And would this help at all protect the rims from this type of damage?

 

[DrEskimo]

Wouldn't advise it. Not only will it not given you substantially more tyre wall to protect it, but the wheel will increase in size too, which is not advised. Throws the speedo out and gets all messy when insurance companies start stiffing about...

Could look at alloygators?

Or get electric folding mirrors to get the dipped wing mirror function?

Or get the Mrs to pay for the refurb to deter her from doing it again

 

[capitano]

Hi thanks for the quick reply. so does the move from 30 to 35 make a big difference to speedo - would that be faster or slower? I guess I'll stick with 30's. Thought the extra meat in the walls might help.

 

[DeanoC]

You'd want to go wider not higher. 30 to 35 will make your wheel bigger and over gear it so one revolution you move further

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[DrEskimo]

Hi thanks for the quick reply. so does the move from 30 to 35 make a big difference to speedo - would that be faster or slower? I guess I'll stick with 30's. Thought the extra meat in the walls might help.

Will increase the overall size by about 4%, which will result in the speedo being -3.85%. This will mean the speedo reads slower than you are actually travelling (Travelling 57MPH when the speedo says 60MPH).

Considering the height of most curbs, you would need a substantially larger tyre profile to clear them. I have 255/35/19 and they are a good inch or so below the curb still. So not only will it potentially cause issues, its not enough to achieve your goal unfortunately...

 

[DrEskimo]

You'd want to go wider not higher. 30 to 35 will make your wheel bigger and over gear it so one revolution you move further

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Yea thats an idea...if you went wider you would get a bit of a bigger rim protection which might help. On 20s I still think it will be high risk, but might be helpful. Many have fitted 275/30 and had no issues. Can look daft at much higher though...

 

[desertstorm]

Looking at a tyre comparison site the difference between a 265/30 and 265/35 tyre is 4% so the speedo would read 4% slower than it does now, 67 mph when doing 70 mph. The 35 profile tyre is 27mm bigger in diameter than the 30 profile which means the car would ride nearly 15mm higher assuming the tyres would even fit.
You are fairly limited in tyre selection as there don't appear to be that many choices of tyre in that size.
Maybe have a look at some of the rim protection systems that exist. There are a few about really designed for people in your situation.

 

[capitano]

Thanks all. The 275 option is interesting. This is running Audi Rs4 20's - do Audi give any latitude re.width or should I just stick with what was on them when I got them and keep my wife away from the car ...

 

[DeanoC]

275 is a about as far as you want to go on a 9 inch rim like the RS4 v spokes.

Like has been mentioned above i showed my mrs how much diamond cutting is and said if she curbs them she is paying and they have been fine since

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[DrEskimo]

Pretty sure the RS4 20s are the same spec as the RS5 20 Rotors (9j X 20 ET26), in which case 275 should fit no problem. They will just have a slightly bigger 'bulge' than your current tyres.

Something like the Goodyear Eagle F1;s have a decent rim protection already, so this should also help.

 

[DeanoC]

Yep they will start to buldge as the tyre is physically wider than the rim at 275 but it will be ok. That buldge will protect your rims from shallow curb kisses.

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