New Wheels, what tyre sizes?

[V8 Devil]

I am just about to buy some new wheels and am unsure what tyre sizes would be the best choice. The wheels are 7x17 front and 7.5x17 rear. I am going to go for Toyos.
My thinking is either
205 40 17 front 225 45 17 rear OR
215 40 17 front 235 40 17 rear.
Any suggestions?
Thanks :

[adavy]

I have the latter and they are brilliant. Worth trying Falken 452s as they work really well on mine. Thats after they have been scrubbed in!!

[V8 Devil]

Thnaks Andy, are your wheels 7x17 all round or 7.5/8.0x 17 rear?

[scorcher]

Have a look here.Find your original size and then find larger size tyres that are very close to your original diamater.( esp. on the rear to keep your speedo accurate )
http://www.toyo.co.uk/productdetail.php?identity=p...

[adavy]

7.5x17 offset 33front and rear. Original Ford RS7 diamond cuts refurbished. Fitted straight on just needed a 5mm spacer on the fronts. Have transformed the car, handles better, more rear grip and for some reason a softer ride!
First 300 miles with new tyres was hairraising but then it settled down. Incidentally I have budget Fullrun tyres on the front (they came with the wheels) and they are absolutely fine.
Andy

[Tahiti450]

The chimaera was usually fitted with 15" front and 16inch rears, when I chnaged my wheels i wanted to retain the slight differential in wheel size (because i think it suits the car cosmetically) so went for 17" front and 18" rears. The wheels i have were only available up to 7.5" width so was limited to that. I run 215/40/17 and 235/40/18 which work very well and maintain rolling circumference at the rear so that the speedo is still accurate.

[URL=http://rides.webshots.com/photo/2139404830057726950OlRUad][/URL]

[V8 Devil]

Thanks guys!

[Bomber Denton]

Tahiti450 said:

I run 215/40/17 and 235/40/18 which work very well and maintain rolling circumference at the rear so that the speedo is still accurate.

Not quite, the rear will stand about 10mm higher than it should.

[Tahiti450]

Bomber Denton said:

Tahiti450 said:

I run 215/40/17 and 235/40/18 which work very well and maintain rolling circumference at the rear so that the speedo is still accurate.

Not quite, the rear will stand about 10mm higher than it should.

Ok, I originally ran 225s and they were about spot on, but 10mm overall is 5mm on the rolling radius which isnt a lot and taking into consideration 6mm of usable tread depth. When mine are well worn they will be within the range of the standard tyre. With new tyres the speedo might under-read by a couple of percent, which isnt likley to be a problem.

[Bomber Denton]

Tahiti450 said:

Bomber Denton said:

Tahiti450 said:

I run 215/40/17 and 235/40/18 which work very well and maintain rolling circumference at the rear so that the speedo is still accurate.

Not quite, the rear will stand about 10mm higher than it should.

Ok, I originally ran 225s and they were about spot on, but 10mm overall is 5mm on the rolling radius which isnt a lot and taking into consideration 6mm of usable tread depth. When mine are well worn they will be within the range of the standard tyre. With new tyres the speedo might under-read by a couple of percent, which isnt likley to be a problem.

I had taken the radius into consideration, it's about 18mm overall on diameter.

[Bomber Denton]

Just another post to be sure I'm right??

O.K. so...

Most Chimaeras are on 245/45x16 on the rear...

245mm x 45% = 110.25mm sidewall height.
16" x 50% for radius = 8" converted into metric = 200mm
Axle to ground (ride height) = 110.25 + 200 = 310.25

235/40x18

235mm x 40% = 94mm
18" x 50% = 9" = 225mm
94 + 225 = 319mm

Phew.

[JR]

Bomber Denton said:

Tahiti450 said:

Bomber Denton said:

Tahiti450 said:

I run 215/40/17 and 235/40/18 which work very well and maintain rolling circumference at the rear so that the speedo is still accurate.

Not quite, the rear will stand about 10mm higher than it should.

Ok, I originally ran 225s and they were about spot on, but 10mm overall is 5mm on the rolling radius which isnt a lot and taking into consideration 6mm of usable tread depth. When mine are well worn they will be within the range of the standard tyre. With new tyres the speedo might under-read by a couple of percent, which isnt likley to be a problem.

I had taken the radius into consideration, it's about 18mm overall on diameter.

It depends how you look at it. Original rear tyre on the Chim 225/55/16 rolling diameter 651mm, Tahiti's 235/40/18: 641mm. Later Chim 225/50/16: 628mm, 245/45/16 625mm.

[spend]

Corin, I would use 1" = 25.4 mm

Dave