Can you fit a 235 tyre to a 7.5" wide rim?

**muffking** · 11th January 2007, 20:10

I have a set of 235/40/18's and a set of 18x7.5" rims. Will they fit ok.

**Drinky** · 11th January 2007, 20:28

Should be ok fella but get one of the boffins on here to work out your rolling radius for you !!!!

**muffking** · 11th January 2007, 20:31

I normally use http://www.miata.net/garage/tirecalcold.html which worked the new tyres out to 79.8" as opposed to 80" on the old 17's

**Drinky** · 11th January 2007, 20:34

Happy days then dont think the width is a problem as i think Nutron runs 235's on his standard 17's !!!!

**muffking** · 11th January 2007, 20:44

Brilliant. I wasn't sure if it had to be an 8" rim, but I'm happy now

**James C** · 11th January 2007, 21:25

A 235 should be ok on a 7.5" rim and it will clear the arches no problem, I've got 235's on my Vauxhall 19's.

**andrewp3883** · 11th January 2007, 21:46

Should be no problem. I have 235's on my 8 inch rims and was asked if i wanted 245 or 255's when they were fitted but was unsure of the arch clearance but needn't have worried. There's loads of room and loads of scope left as my tyres almost have a bit of stretch on them if you know what i mean.

**nutron** · 12th January 2007, 00:15

I do indeed have 235s on what I now know to be 7J

so you should have no problem with them.

P went sideways up a curb and the tyres didn't shift an inch. You might need to increase the psi slightly to achive uniform wear though.

Go for Toyo T1-Rs, they are great in wet and dry.

**muffking** · 12th January 2007, 10:14

Cheers guys. The car manual says that the old 17"s should be around 40psi, roughly what should the 235/40/18's be?

**Maverick** · 12th January 2007, 10:29

You want to base the tyre pressures on VXR 18" rims, these also are 235 40 18" tyres. You would have no problems in over all tyre diameter, but regardless to what people have said you are actually on the limit with a 7.5" rim.

This is why Vauxhall decided to fit 225 45 18" tyres on the 7.5" rim and 235's on the 8" rim. If you look at all the manufacturers out there, they all use an 8" rim for 235 upwards.

I always base my theories on what the manufactuer works with as they spend hundredsof thousands of pounds on research and development.

My concern would be the heavy weight of the 3.2 with this wheel and tyre set up.