differences btwn 245/40/17 and 225/40/18

[ddub]

For those of you that have experience with both, I was wondering what the tradeoffs are (performance wise, not looks) between a 245/40/17 and 225/40/18.

 

Lets assume the tires are something like Ecsta SPTs. For rims, lets say the enkei NT03-M rim:

17x8 5x100 bolt pattern weighs only 18.3 lbs each

18x7.5 5x100 bolt pattern weighs only 17.9 lbs each

17" tire weight 26 lbs

18" tire weight 24 lbs

 

combo weight

17" 44.3

18" 41.9

 

total difference 9.6lbs

total rotational difference (7/8 edge biased): 14.4 lbs

 

*edit for more info*

17" diameter: 24.7" (+.1")

18" diameter: 25.1" (+.5")

*end edit*

 

Type of driving: sprited, non-track, stage 0 currently, gpmoto coilovers on order

 

Hopefully that is enough info I am really undecided on this and could use some help on determining factors that I can't look up. Would the handling difference be noticable? Ride difference? etc.

 

and yes, i've read all Xenonk's faqs, etc. (oh and searched too!)

 

Thanks in advance...

 

-doug

[praedet]

OK, using the stuff you gave me and assuming a generic 6 spoke wheel like the SSR for shape, you save are 1 lb lighter (per corner) with the 18", and add 1.5 lbs with the 17". Your effective weight change for the vehicle is an added 16 lbs for the 17", and losing 1/2 lb for the 18". If the LGT does 0-60 in 6 sec (no clutch drop) then the 17" combo does it in 6.03 sec, and the 18" does it in 5.999 sec.

 

The car would ride better with the 18" combo because of a larger sidewall, and less unsprung weight. But...

 

The 17" would have more grip.

 

Handling diff. would be noticeable.

 

Personally, I wouldn't do either. I would look for a lighter rim and go with a 235/40-17 on a 17x8 rim. That gives you a lot of grip and yet will minimize unsprung weight.

 

Ted

[PGT]