51 Reply by MZAVARIN (edited by MZAVARIN 2016-12-13 02:41 PM)

  • From: Plymouth, MA
  • Registered: 2013-06-07
  • Posts: 786

Re: Tires poking past fender

Also, the law of unintended  consequences is hard at work when making these kinds of changes.  We recently went from a 15" to a 17" wheel so that we could go from a 205 wide tire to a 225.  The difference in cornering forces was significant.  To the point that we now have an oil starvation problem in longer left hand corners and we spun our first wheel bearing, ever.  Both, it would seem, the result of higher cornering forces.



Yes...very good, informative links.

Now this discussion is getting fairly cerebral and theoretical for me....but I put on 225s on my 15 inch rims (BFG Rival non-S)....so then would 225s work better on 15 inch rims or 17 inch rims?  Why didn't you just put the 225s on your 15 inch, smaller rims?  Which would (likely) decrease your unsprung weight??

Or would the ratio of sidewall to wheel radius/diameter be more beneficial with a 15inch vs 17 inch rim? For sidewall flex, and cornering, and such? 
And does the width of the wheel matter much?  I believe the 225s could be mounted on a anything between a 7 and 8.5 inch rim?  Mine are on 7 inch wide rims...

MarioKart Driving School: 1987 Honda Prelude Si (Opus #28) 
Loudon, NH 2014 - Millville, NJ, Lightening 2019 (RIP)
New and improved: 1987 Honda Prelude Si (Opus #11) Pittsburgh, PA 2021 - ??
and finally won something, Class C Win: Loudon, NH 2022
  • gump
  • gump
  • Ripened Lemon
  • Offline
  • From: el aye, so cal
  • Registered: 2011-06-01
  • Posts: 330

Re: Tires poking past fender

We really like the Dunlop Direzza's and in 15" the widest available is 205.  I would have liked to use 16" wheels but the volvo bolt pattern (5 on 108mm?!?!) leaves very little choice in wheels and 16"s are becoming few and far between in the aftermarket wheel space. That's how we ended up with 17"s; that and the fact that we wanted a wider rim to go with our wider tires.

There is a ton of internet conjecture as to how wheel diameter, sidewall height, relationship between tire and rim width, etc. affect the the G's a given car can make on a skid pad.  If you think about it long enough you can give yourself an aneurysm.  Without the CFD computing power of an F1 team, the only way to really know is to try it. 

Also, if you change the overall circumference of your tires you also change the final drive ratio of your drive train.  Bigger tires raise the drive ratio which can make your vehicle more sluggish, to use the technical terminology.  I spent many, many hours in junk yards looking for a ring and pinion that would return our overall drive ratio to what it was with the smaller tires.

MZAVARIN wrote:

Also, the law of unintended  consequences is hard at work when making these kinds of changes.  We recently went from a 15" to a 17" wheel so that we could go from a 205 wide tire to a 225.  The difference in cornering forces was significant.  To the point that we now have an oil starvation problem in longer left hand corners and we spun our first wheel bearing, ever.  Both, it would seem, the result of higher cornering forces.



Yes...very good, informative links.

Now this discussion is getting fairly cerebral and theoretical for me....but I put on 225s on my 15 inch rims (BFG Rival non-S)....so then would 225s work better on 15 inch rims or 17 inch rims?  Why didn't you just put the 225s on your 15 inch, smaller rims?  Which would (likely) decrease your unsprung weight??

Or would the ratio of sidewall to wheel radius/diameter be more beneficial with a 15inch vs 17 inch rim? For sidewall flex, and cornering, and such? 
And does the width of the wheel matter much?  I believe the 225s could be mounted on a anything between a 7 and 8.5 inch rim?  Mine are on 7 inch wide rims...

10x loser (Arse-Freeze '11 - Vodden '15) 1x WINNER! Arse-Freeze '14 in the Watermelon Volvo Wagon
Swedish Knievel Skycycle('90 Volvo 740 Wagon)