firelizard

iTrader: (1)

235/40-18 is 2mm taller than the stock 17" package. 245/40 is 10mm taller. You can use four of either one, or stagger them. Your preference.

8M6

iTrader: (2)

That is true. One thing that always puzzled me though is that the stock GS400/430 16" tire diameter (225/55/16) is taller than the 17" package (235/45/17). Then the GS300 got the even taller 215/60/16 through 2002-03.

My only thought is that Toyota wanted more clearance between the inner edge of the tire and the spindle arm up front with the 17s, because 245/45/17 is a perfect match for 225/55/16, and 8" wide wheels are within spec for 245/45/17 tires.

By extension, when going up to 18", 245/40/18 just makes the most sense to me because it matches 245/45/17 and 225/55/16.

silverbul

245/40 in the front is the recommended size I was told by tirerack expert to handle the load capacity of our vehicle. I tried 225/40, 235/40 and kept getting sidewall lumps on the inner tire. And was told that's the reason why. The rear was 265/35

firelizard

iTrader: (1)

That's a good point, and load index is often overlooked. The load index of 95 (1521 lbs/tire) that most sporty 235/40-18 have is sufficient for the GS though. The 245/40-18 usually have a load index of 97 (1601 lbs/tire). Tire Rack suggests tires with a load index as low as 93 (1433) in some cases, which puts me at ease as far as using a tire with a 95 load index. The gross vehicle weight rating of a GS430 is 4706 lbs.
So with 18" wheels you have a lot of flexibility in tire choice.

Aeok18109

i already have the wheels unfortunately. how much of a spacer do i need to bring these flush to fender? i guessed 30mm. would that allow me to run a wider tire such as the 265 or should i return the 2 and get 2 more 245/40/18? i still wouldnt really be able to rotate since its a staggered wheel right? im on bone stock suspension atm. the plan was to use this setup temp until i could get coils and later 3 piece baller wheels

firelizard

iTrader: (1)

30mm would bring you closer to the fenders without needing to roll or cut them. I still advise against 265 on a 8.5" wheel, especially since you're saving up for better wheels and coilovers so this entire endeavor is just setting you back by hundreds of dollars that you could have put towards coils and splits. But since you've already spent the money buying 265s, I guess go ahead, it's probably fine. You can reuse them on your new wheels if you get 18s. 245/40 is what you should have got in the first place, for this particular setup. You would have been able to rotate the tires if you had the same size all around, but you'd have to get them unmounted, remounted, and rebalanced. The only way to truly be able to rotate your wheels and tires without remounting them is by having four of the same wheel and tire combination, with non-directional tires. This entire process should serve as a lesson as to why researching first and buying second is a good idea.

Aeok18109

thanks. i will most definitely keep that under advisement and may change some plans up to rectify the situation sooner rather than later. i appreciate all your help.

Aeok18109

forgot to ask. would i need a 30 mm spacer for front and rear or just rear? the spacer wouldn't change the offset of the wheel correct? it would still BE a +45 F and +50 R ... or would i measure it differently since its closer to the fender now?

firelizard

iTrader: (1)

Spacers change the effective offset, that is their only function.

Wheel offset - spacer thickness = new offset.

8M6

iTrader: (2)

firelizard basically answered everything already, but you ought to test fit the new wheels and tires to see exactly how far you are from being flush to the fenders and go from there. Don't make the same mistake you made with the tires. You're not at risk of rubbing, so run what you have now, then measure before deciding on a spacer size.

I can tell you that my 18x8.5" 45mm up front with 245/40/18 is pretty much flush with the front fender. The same combo is still slightly tucked in the rear, but not by a large enough amount to bother me. I don't care very much about being flush with the fenders as long as they don't exceed the fenders and I personally don't like using spacers.

You have 18x8" 45mm up front. You lose 0.5" on the overall wheel width compared to my wheels, but because you have the same front offset, that reduced width corresponds to -0.25" on both the inner and outer edges of the rim. 0.25" is 6.35mm. The nearest standard spacer sizes that are also available as Toyota hubcentric are 5mm and 7mm. 7mm puts you in the unenviable position of needing longer wheel studs to safely run spacers of that size. I would rather step down to 5mm so there are still enough usable threads on the OEM studs.

To be flush in the rear, you need approximately 20-25mm more than the front, but with 265 width tires, you're 10mm closer to the fender than I am with 245. However, you also have to subtract 5mm for the 5mm higher rear wheel offset. The remaining 15-20mm will be your spacer width, and spacers in that size should come with wheel studs. Again though, measure for yourself first and don't solely rely on my calculations.

Aeok18109

you guys are absolute wizards. thank you so much. i will keep watching videos and reading until i understand and grasp this concept so i can stop asking questions that like you said have been answered before. i really do appreciate the help.

silverbul

to give you a idea of the look you're trying to get. This is my current set up. I know this segment is about 18s but I'm running 19s now. I'm using the 5mm spacer in the front to clear the LS400 calipers. In the rear I'm using 25mm spacer & its flushed with the fender. Basically the front & rear wheels are flushed with the fender

firelizard

iTrader: (1)

^ need to post wheel widths and offsets for that to help

silverbul

19x9 in the front 45mm offset, 19x9.5 in the rear forgot the rear offset. OEM rims off 2014 GS F sport.

silverbul

Wheel flushed with the fender