Hey need a bit of advice...

Got a 2nd set of rims for minor trackwork, and its 17x8 +30.
Want a set of semis on them of course, but wondering what size should I be looking at and the benefits of each?

Stock size is 235/45/17 for evo9 standard rims, so I was thinking I'll get the semis in that size.

But from the limited knowledge I know, wider = more grip, but less acceleration.
and narrow = opposite.

But what about the middle number? What if i go 235/40/17 or something?
How would that affect the handling or whatever else it affects? lolz

 

A 235/40/17 tire will be shorter, I've seen people run this setup without any problems. It will give you a slightly smaller sidewall which can be beneficial in reducing sidewall flex, you'll also have a shorter gear ratio which can help or hurt depending on the track that you're running on. If there's a long straight then you may run out of gear before the end, however if there is no risk of this happening then the shorter gearing will help you accelerate out of the turns faster. IMO you should go with a 245/40 it'll be a little wider and a little shorter than stock size but not as short as the 235/40. Some will argue that a wider tire that bulges on the narrower rim will cause unwanted flex but I think the benefit of having the extra rubber in the ground will help even more.

 

track - 255/40/17

 

Many have used 245/40-17 with no fit issues as well. 255's really like an 8.5" wheel.

 

245/40/17?
Sounds like the way to go with 2 votes lolz

255 does sound like its a bit too crazy considering semis are already 'fatter' compared to normal tires.

As for running outta gears, that's not a problem with the tracks here in Australia (at least not something I've run into yet with my slow-evo lolz

I guess i'll see it all depends on pricing.... I'll go with a cheaper option as I'm not pro, and i'm most likely not going to feel 'massive' amounts of differences.

But a 235/45 or 245/45 would be still 'ok' right, or is that a big no?? (i'm jus thinking of the choices i'll be left to choose when I get prices)
The main problem down here in Australia is not too many people buy semis, so rare sizes are ALOT more expensive than common ones, but if the '40' has huge significant difference, that'll become a big factor lolz

 

There won't be a night/day difference between a 235 and 245. Only 1/4" wider on each side with the 245's. If the larger sizes cost a lot more I'd just stick with 235's.

 

i just picked up a set of dunlop star specs, the 235/45's and 245/45's were the same price (factory 17x8's). the 245/40's were considerably more so i went with the 245/45's, i have the tein s-tech springs on my car, and they rub just a bit, rolled my fenders, gonna have to cut the fender wells a little bit, but they are amazing.

 

I would get some tougher springs before rolling+cutting fenders.

 

I guess i'll just stick with the cheapest option, unless the 40 ones are like $1 more expensive or something rediculous like that haha

 

245/40

 

It's my opinion that a 45 sidewall is too tall and gives too much flex. I'd recommend a 40 side wall and the widest tread you can fit and or afford.

 

Alrighty gonna give the 40 a try if I can find some!
The stupid thing is the market here in Australia is tiny, so you can only get the more popular sizes which seems to be the 45 >< ><