Taller/wider tires than stock - experiences?

[Scubaboo]

Nearing tire replacement time and checking options.

I am possibly looking to go wider in preparation for something like a stage 1 tune and/or taller for a bit better ride.

I know a few people here have/had gone up in size and I have an idea of what sizes fit.  But I have some questions I didnt see answers to in their threads.

First, how was acceleration impacted going taller in tire size from 225 45 to 235 45 or 245 45?  

Second, any negatives like tramlining going a bit wider?  I was wondering if it would be a problem but Sti's run 245 with no problems I've seen in a cursory search so I am thinking it shouldnt be a problem here with very similar suspension design?

I know offhand @Humble Rumbleruns bigger than stock, and Perscitus too but I dont know if he still goes on here.

Currently thinking to move from stock size 225 45 Bridgestone RE003's (Firehawk Indy 500's in North America) to 235 or 245 Pilot Sport 5's.

[Humble Rumble]

I forget if you're on stock wheels or aftermarket, but assuming stock, you can move to a 235/45/18 on the stock GT wheels with no issue if you want a little more chunk and meat. 245/45/18 or larger, you'd need to go to a difference size wheel.

If you're on aftermarket wheels, I'd need to know the full specs to adequately advise. That said, I've had enough difference size wheel setups on mine that I can give you pretty solid guidance with picture examples so you can sort out how you want to go. Willtheyfit.com is also an extremely useful tool that I've used literally hundreds of times to figure out some pretty complicated fitment math. 

Factory GT wheel size is 18x7.5 +55 on 225/45/18. Here's a comparison between that and moving to a 235/45/18 on the same wheels. Very small change overall, handling will be slightly improved and ride will be slightly cushier. Car will also sit slightly taller but less than 5mm, and the larger tire will visually fill the wheel well a bit more, so it won't look bad. 

 

Next, here's a comparison between going to 245/45/18 vs stock. For this size tire, I'd recommend *MINIMUM* of an 8" wide wheel, preferably 8.5" if possible. This is a substantial size up as far as total diameter is concerned. For reference, 245/45/18 and 245/40/19 are as close as makes no difference to perfectly identical total diameters (677.7mm vs 678.6mm, 0.9mm difference). I also changed the offset to +45, as offsets anywhere between +38 and +48 are very common for 5x100 8.5" wheels (remember, the lower the number, the FURTHER out the wheel is, and it goes in mm. So an 18x8.5 +45 wheel and an 18x8.5 +20 wheel will fit exactly the same tire, but the later will sit 25mm/~1" further outset than the former).

I'm unsure on the JDM/World cars, but on the USDM cars at least, this total diameter (~678mm) put the cars almost perfectly at GPS-accurate speed (factory speedo reads about 1.5-2mph slower than GPS). This total diameter also looks really good as far as filling the wheelwell, but unless you're lower a bit, can make the car look a little tall/monster truck-ish. Handling will feel quite nice and quite grippy compared to stock. Acceleration will ever so slightly suffer from the higher weight, but doubtful enough to notice. When I ran this size, I was also on 31lb wheels and my next setup was a smaller tire size on 19lb wheels, so I'm not the best litmus test for accel difference. Still felt fast enough on the big ones. 

Here is my own car on 19x8.5 +45 240/40/19, and former member Timothy.B's car on 18x8.5 +45 245/40/18, which equals essentially identical fitment. Both of us are on Eibach springs here (roughly 1" drop). Last picture is also my own car on this wheel setup at both stock height and lowered 1" on Eibachs, to demonstrate the monster truck-ness. My wheels were Five:AD S7F's (discontinued, hard to find. also very heavy), Tim's were Enkei TS-10. 

 

If you're wanting to go wider and more aggressive, with a total diameter close to stock diameter, here's two more examples: 245/40/18 on 18x9 +38 (Konig Rennform) and 255/40/18 on 18x9.5+43 (Enkei RS05RR). You can also play with tire size here a bit, 255/35/18 and 265/35/18 are very common sizes to use around this size range of wheel, and I've also seen 265/40/18 and 275/35/18 used as well.

 

Keep in mind though and USDM cars can run slightly bigger maximum fitments than JDM cars can, but I have seen 9" and 9.5" wheels on JDM body cars. Depending on the wheel/tire combo used and just as a rough guide, for wheels wider than 8.5" and of a higher offset than +45, I'd recommend looking into fender rolling. 

[Scubaboo]

Thank you, Humble, for answering with your usual detail!

I currently have 225 45 R18's on 18x8 et 40 Rota Gravels so I figure I can go up to 245 properly.  Looking to work with the wheels I have at the moment.

I used to be pretty low on KW coilovers but the long bumper overhangs were limiting where I could bring the car lol!  So I went back to factory sport package Bilsteins which are pretty high.

Right now I want to try wider and taller so 245 40 is out for now.  I am choosing between 245 45 and 235 45, but I am afraid of affecting acceleration with too tall a tire, so 235 45 has the edge at the moment.

 

Edited April 26 by Scubaboo
Pic

[Humble Rumble]

235/45/18 on 18x8 +40 will be a very nice look and the best compromise between improved grip/handling and improved ride without sacrificing much in speed performance in my opinion. I'd say go that route rather than 245/45. 245/45/18 *can* fit on an 8" wide, but it will look a bit too donut-y and would be more at home on an 8.5" wide instead. 

[Scubaboo]

That is what I feel at the moment too.  It's encouraging to hear the same from someone who has experience with a lot of different wheel and tire sizes on our cars!

Another thing I realized reading you mention that size can fit on the stockers is I wont need to look for a new wheel for my spare in the trunk.

[Plastixx]

46 minutes ago, Scubaboo said:

I am choosing between 245 45 and 235 45, but I am afraid of affecting acceleration with too tall a tire, so 235 45 has the edge at the moment.

The wheel/tire combo I have is slightly smaller than stock. My car being NA, I figured even a tiny bit of acceleration gain would be welcome. 235/45 on 17x8 +35. Went with 17 because the roads are trash here.

[Scubaboo]

31 minutes ago, Plastixx said:

The wheel/tire combo I have is slightly smaller than stock. My car being NA, I figured even a tiny bit of acceleration gain would be welcome. 235/45 on 17x8 +35. Went with 17 because the roads are trash here.

Now that you mention it, I'm curious if you could feel the slight acceleration advantage the slightly smaller tire gives?  Was there a perceptible difference from stock size for you?

I wouldnt mind slightly smaller but wider like 245 40 r18, but the stock 225 45 already looks small on the slab sides of the 5th gen.  

Maybe if I were still on coilovers but stock height makes stock look even smaller lol!

[cww516]

I used to have 245/45R18 tires on 18x8.5 +45 wheels as my summer set, and I wouldn't say it was a big difference, but the butt dyno did detect a slight improvement in acceleration on my stock-size snow tires relative to the summer tires.  I went with 245/40R18 when I got new tires put on about a week ago, though, for whatever that's worth to you.

Also, I seem to remember seeing that someone was running a 245/45R18 on an 18x8.5 +38 wheel without having to modify the fenders- might have been Swannee225?  I feel like he had the same wheels as me in a different offset, might be why that's sticking out in my mind.  Wonder if I can find that again...

[Scubaboo]

1 hour ago, cww516 said:

I used to have 245/45R18 tires on 18x8.5 +45 wheels as my summer set, and I wouldn't say it was a big difference, but the butt dyno did detect a slight improvement in acceleration on my stock-size snow tires relative to the summer tires.  I went with 245/40R18 when I got new tires put on about a week ago, though, for whatever that's worth to you.

Also, I seem to remember seeing that someone was running a 245/45R18 on an 18x8.5 +38 wheel without having to modify the fenders- might have been Swannee225?  I feel like he had the same wheels as me in a different offset, might be why that's sticking out in my mind.  Wonder if I can find that again...

Thanks for sharing your experience here!

If the stockers didnt look small already at stock height I would probably be going with 245 40 r18's like you did.

Perscitus was running 245 45 r18s too on similar wheel specs I think.

[Scubaboo]

I've also started to wonder why Subaru went with 225 45 r18 on the sporty 5th gens, when the WRX/STI's got 245's.  With pretty much the exact same suspension geometry.

[Scooby Fan]

I am currently running OZ Racing 18x8 45 offset and Michelin Pilot Sport A/S 245/40/18......could not be happier...great traction wet or dry and a sporty but comfortable ride. In winter I return to my OEM 17" wheels with Nokian WR G3's 225/50/17...they are a great winter tire but a bit squishy feeling if driven hard on dry roads.

 

Edited yesterday at 12:38 AM by Scooby Fan

[Scubaboo]

8 hours ago, Scooby Fan said:

I am currently running OZ Racing 18x8 45 offset and Michelin Pilot Sport A/S 245/40/18......could not be happier...great traction wet or dry and a sporty but comfortable ride. In winter I return to my OEM 17" wheels with Nokian WR G3's 225/50/17...they are a great winter tire but a bit squishy feeling if driven hard on dry roads.

 

I'd probably be going that size if I were still on coilovers but at stock height now and want a bit of sidewall along with the width.

Currently leaning towards 235 45 r18 Pilot Sports but out of stock right now.