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Going from 40/18 to 45/18

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That will stand me approx 1 inch taller? I could use that to help front lip scraping.

I'm slightly lower on R springs (don;t fancy going back to stock springs to raise the height or to remove my front lip) and have 7mm front spacers and 15mm on the rear. Any concerns with tires rubbing the wheel well?

Apart from riding taller, any major handling changes for road use (doubt it but thought I'd check), fast cornering and for spirited occasion B-road drives. No tracking.

Thanks all.

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8 hours ago, Aaron said:

Your speedo will read 4% faster as you've increased the circumference of the tyre.  This would be my primary concern.

Thanks.  This is a risk for the many speed cams here but manageable.

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1 hour ago, Liongolfer said:

Appreciate it if you can explain more.  I don't know what this means.


Total drive is calculated using the tyres.  By increasing the tyre circumference, you are decreasing your total drive ratio which means your car will accelerate more slowly than it would with 40 profile tyres.  You will, however, increase your potential top speed (at least from a gearing standpoint).


TL;DR: Larger tyres mean all gears will be longer and your acceleration will be slightly slower.


My advice would be to find an alternative to your front lip scraping rather than increase your tyre profile.  You can buy "armour" or "shielding" (some plastic with adhesive, really) that sticks onto the front bumper/lip to save it from scraping but that does, of course, make the lip/bumper even lower than before.  A low car comes with these challenges and I've always found adjusting my driving/approach to be more effective than anything else.

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