Wider, lower profile tires on stock 18" base rims

rclarkbow

Hi guys,

I've been doing a lot of research about upgrading my tires.

Stock 18" base wheels

I am part of an auto cross club and also do track days, but also drive the car on the street occasionally in the summer only (no longer a daily).

My general g-max RS tires have worn down so it's time to replace tires. I'm hoping I can get away without buying new wheels just yet.

Nearly everyone who is competitive in my club is running the Falken RT-660s extreme summer

https://www.tirerack.com/tires/falken-azenis-rt660

Based on sizes, it looks like the only setup that will work will be the following:

Front: 245/40 18
Rear: 275/35 18

I realize this gives me a smaller tire diameter and will gear it down, but these tires aren't available in 245/45 and 275/40 (which I've seen others run on stock rims on here so I'm not concerned about the width fitting the wheels). The diameter of the front wheels and tires will be slightly larger than the rear, as it is on all stock 370z models (base and sport).

Will these lower profile tires work / perform well?

I know the speedo will be off, shift points, gearing down slightly etc. but will they perform all right? My heart is kind of set on these tires as everyone runs them and I feel like it might even be beneficial to use lower profile for performance.

Additionally they really don't make extreme performance summer tires available in the 245/45 18 / 275/40 18 setup or I'd probably just go with that...so asking if the painted on Falken option will work well. If anyone has any better ideas please let me know!

Thanks

JARblue

Sure you can fit those tires on the stock wheels. Not the best fit since they'll probably have some stretch. But it sounds like you have already made up your mind.

Personally, I would save up for some properly sized track wheels. If you get a square setup you can rotate the tires for longer life.

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SeeThruHead

245/40 would fit well i think. It's wider than the stock 225/50 only 4% difference in diameter tho.

275/35 is similarly wider than the stock 245 widths. with 4% difference again.

I think it's a pretty perfect set of tires to run on the base 8/9 inch wheels.

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JARblue

I was comparing to 245/45 and 275/40 since OP mentioned those sizes but I forgot the stock base tires are 225/50 and 245/45.

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rclarkbow

Thanks so much for this input. I have a spreadsheet and was calculating the percentage change of the diameters as well, so I certainly appreciate that! 4% is probably not going to be that big of a deal based on my experience / common sense. Speedo will most likely read about 104 when I'm doing 100mph, again no big deal.

I ended up only needing front tires so I cheeped out and just replaced two of the existing Generals for now. Probably next year I'll get the Falken's all around. I'm also now considering a more aggressive wheel setup with a set of Enkei wheels specifically for the track in the spring, so you might see me posting about that next year.

Thanks everyone! I'm still torn about getting a second set of wheels for the track, but it's great to know that the Falken's would work on my base wheels if I end up going that route!