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Avalon

18” wheels on a 4.2?

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The standard spec for the 4.2 was up to 17” with a 225/55/17 on a 17” 7J/ET45 rim. My question is simple, has anyone run anything bigger than 17” on a 4.2, such as a the later 18” 7.5J/ET45’s from the 4.3? I’ve just been told we have a set of 18’s 800 miles round trip away if i want to drive down and get them out of the garage, but it’s a long way to find out they don’t fit or rub 😄

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I can see an 800 mile drive in my future... c’mon people, think of the environmental damage, let alone to my foot when I kick said boxes of rims if they don’t fit 😉

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I've never owned a 4.2 let alone tried 18" wheels on one so all I can offer is some thoughts that you've probably already thunk ... 🙂

Standard sizes on a 4.3 were 225/65 R17 and 235/55 R18 - both with a 45 offset so that part should be OK. The 18" have a diameter of 716 mm and a width of 235 mm - compared with your 225/55 R17s that have a diameter of 678 mm and a width of 225mm. So, in terms of width the 18" will stick out 5 mm more,  and intrude 5 mm more, than you current wheels. The difference in diameter is 38 mm so will need an extra 19 mm within the wheel arch.

So, if you took a short length of 2x1 and could fit the wider side around the inside between your wheel and the arch the 18" wheels would probably fit. If the narrower side doesn't fit or is 'tight' you might expect problems and save yourself the 800 mile round trip.

The 18" wheels will also affect the speedo readings - you will be going about 6% faster than previously for any given speedo reading. That's probably OK given that the speedo probably over-reads by more than that in the current configuration but it's another consideration.

Obviously you would need to inform your insurers ... 😉

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I’ll have a play about with some measurements this weekend, i’d be going from 235/60/16 and have literally just fitted new rubber, so not planning on swapping over any time soon, but next time Costco have an offer on its easier to take them along if they’re not 400 miles away.

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1 hour ago, Avalon said:

 i’d be going from 235/60/16

235/50/18 would be very close in terms of rolling radius. The inner rim would be 12.7mm further in & the outer 12.7mm further out unless you are going to go for a different offset.

https://www.willtheyfit.com/index.php?width=235&aspect=60&diameter=16&wheelwidth=6.5&offset=45&width2=235&aspect2=50&wheel_size=18&wheel_width=7-5&offset2=45

225/50/18 would be another close option in terms of RR.

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After a bit of digging, apparently 18” and 8J isn’t a problem (with a suitable tyre choice), but ET40 is as far as after market suppliers seem to go, that could leave me needing spacers, and that’s another thing to mention to the insurer. I suppose I should reconcile myself to refurbishing the stacks of 16’s I have kicking about. Thanks for the advice 🙂

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