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The mkiv Supra Owners Club

Tyre profile choices


berg

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For example..

The top picture shows a 225 40 18

The bottom picture shows a 305 30 18

 

The 305 30 actually has a larger depth sidewall than than 225 40 due the the overal percentage.

But using your statement you'd say that the 30 profile tyre is bad because it doesnt have enough 'squidge' even though it has more than the 40 profile tyre which you say is good?

 

Do you get what im saying?

 

image

 

image

 

 

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You cant paint all tyres with the same brush regarding sizes though.

The profile size is a percentage of the width.. therefore a 295 30 18 wont have the same side wall depth as a 225 30 18 thus making your coment completely redundant?

I may be wrong here and i dont claim to be any sort of tyre size genius but i dont understand how you can say 30 profile tyres are bad without also stating a width?

 

 

/QUOTE]

 

Wider tyres require wider wheels and because deep dishes are trendier than correct offsets is where it can soon wander into tits-up territory.

Edited by David P (see edit history)
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Increasing the width of the tyre does increase the sidewall height, but that is just one element.

 

Suspension travel alters the wheel/road angle and regardless of regained tyre sidewall height and final gear ratio, the "lateral" squidge is proportionally less with a 30 than it is with a 40, which can result with lack of road contact for the outer and/or inner edges by up to 50mm of tyre road contact.

 

Incorrect wheel offset exaggerates this.

 

Lowering more than 10 - 15mm exaggerates this.

 

Incorrect geometry exaggerates this.

Edited by David P (see edit history)
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Chris may soon pop up and say similar things, yet with the correct technical terminology?

 

I run 285 40's on 18's, which is max width for my 10" Borbet TTE's, they have the correct offset and everything fits perfectly with a minor lip trim. (275 40's fit without trimming)

 

With an N/A 4.083 Torsen diff, this wheel tyre combo gives near as dammit same ratio as 3.769 T.T. auto stock wheel/tyre sizes.

 

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Edited by David P (see edit history)
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