Title: Best size tyres?
Post by: Steve Burnett on February 17, 2005, 10:45:46 PM
Post by: Steve Burnett on February 17, 2005, 10:45:46 PM
What would be the best size of tyres to fit 17x8.5??
245 45 R17???
245 45 R17???
Title: Best size tyres?
Post by: banned advertiser on February 17, 2005, 11:07:28 PM
Post by: banned advertiser on February 17, 2005, 11:07:28 PM
235\'s
Used that size on fronts and wont be over stretched on those rims sizes, 245 would fit.
Used that size on fronts and wont be over stretched on those rims sizes, 245 would fit.
Title: Best size tyres?
Post by: Steve Burnett on February 18, 2005, 04:58:12 PM
Post by: Steve Burnett on February 18, 2005, 04:58:12 PM
Any reason why you might want 235\'s instead of 245\'s?
Pic of my wheels, im well happy with them :D
Pic of my wheels, im well happy with them :D
Title: Best size tyres?
Post by: Shark on February 18, 2005, 05:29:11 PM
Post by: Shark on February 18, 2005, 05:29:11 PM
235/45 17 will give yuou a rolling diameter almost exactly the same as stock 225/50 16
245\'s would make your speedo and odometer a bit iffy.
245\'s would make your speedo and odometer a bit iffy.
Title: Best size tyres?
Post by: Steve Burnett on February 18, 2005, 05:42:42 PM
Post by: Steve Burnett on February 18, 2005, 05:42:42 PM
Now thats a good reason.
Title: Best size tyres?
Post by: Steve Burnett on February 20, 2005, 06:07:31 PM
Post by: Steve Burnett on February 20, 2005, 06:07:31 PM
Any effects on handelling running 235\'s as opposed to 245\'s?
Title: Best size tyres?
Post by: cruiser on February 20, 2005, 11:15:41 PM
Post by: cruiser on February 20, 2005, 11:15:41 PM
OMG.... where did you get those wheels ? Those are THE SEX!
How much ?
How much ?
Title: Best size tyres?
Post by: Shark on February 21, 2005, 09:08:31 AM
Post by: Shark on February 21, 2005, 09:08:31 AM
QuoteOriginally posted by Steve Burnett
Any effects on handelling running 235\'s as opposed to 245\'s?
Shouldn\'t make a big difference. stock is 225 all round so handling should be fine.
Title: Best size tyres?
Post by: ro284 on February 21, 2005, 09:33:58 AM
Post by: ro284 on February 21, 2005, 09:33:58 AM
225x50x16 is the same size tyres as a Ford Probe, (FWD) Mine are fronts 235x45x17, rears 255x40x17, when i replace the rears it will be with 265 Eagle F1! IMO i think the extra power of an RX7 need those size tyres and they suit the car very well, i dont think you would see a Porsch with 225 on the rear.
Title: Best size tyres?
Post by: John Yorke on February 21, 2005, 04:50:43 PM
Post by: John Yorke on February 21, 2005, 04:50:43 PM
My stock 17\'s came with 235X45 front and 255X40 rears
Title: Best size tyres?
Post by: kevint on February 21, 2005, 05:03:23 PM
Post by: kevint on February 21, 2005, 05:03:23 PM
QuoteOriginally posted by John Yorke
My stock 17\'s came with 235X45 front and 255X40 rears
Just as Mazda intended for 17x8 at the front and 17x8.5 at the rear
Title: Best size tyres?
Post by: Shark on February 22, 2005, 09:17:31 AM
Post by: Shark on February 22, 2005, 09:17:31 AM
The FD\'s which came out of the factory with 16" rims had 225/50/R16 and the drive on them is fine for standard power output.
putting 265\'s on will throw your speedo and odometer off.
Steve, if you haven;t already bought tyres, probably as well to stick with Mazda sizes of 235 front and 255 rear.
From the comments above, sounds like they would fit fine on your wheels.
putting 265\'s on will throw your speedo and odometer off.
Steve, if you haven;t already bought tyres, probably as well to stick with Mazda sizes of 235 front and 255 rear.
From the comments above, sounds like they would fit fine on your wheels.
Title: Best size tyres?
Post by: Steve Burnett on February 22, 2005, 01:45:30 PM
Post by: Steve Burnett on February 22, 2005, 01:45:30 PM
Not bought them yet.
I thought 265 were for 9\'s at the rear? 225\'s for 8\'s at the front?
I want to keep the spedo as close to the correct reading as possible.
I thought 265 were for 9\'s at the rear? 225\'s for 8\'s at the front?
I want to keep the spedo as close to the correct reading as possible.
Title: Best size tyres?
Post by: Shark on February 22, 2005, 02:04:35 PM
Post by: Shark on February 22, 2005, 02:04:35 PM
PM\'d you my number mate, give me a call.
Title: Speed Adjustment
Post by: RX-HEAVEN.COM on February 22, 2005, 05:37:30 PM
Post by: RX-HEAVEN.COM on February 22, 2005, 05:37:30 PM
If you need to dial in the correct speedo reading, there is an adjustment pot on the speedo circuit board.
We check road speed with GPS at say 3000rpm & then with the back of the car on axle stands adjust this trimmer until the speedo reads the correct speed at 3000rpm
Its as easy as that!!!
We check road speed with GPS at say 3000rpm & then with the back of the car on axle stands adjust this trimmer until the speedo reads the correct speed at 3000rpm
Its as easy as that!!!
Title: Best size tyres?
Post by: Steve Burnett on March 17, 2005, 06:51:00 PM
Post by: Steve Burnett on March 17, 2005, 06:51:00 PM
Okay then, its going to be:
235 x 40 x 17 or
235 x 45 x 17
What reason can you give me for going for one above the other?
Why not 235 front and 245 rear????
235 x 40 x 17 or
235 x 45 x 17
What reason can you give me for going for one above the other?
Why not 235 front and 245 rear????
Title: Best size tyres?
Post by: Steve Burnett on March 19, 2005, 10:27:56 AM
Post by: Steve Burnett on March 19, 2005, 10:27:56 AM
???
Title: Best size tyres?
Post by: Shark on March 19, 2005, 01:18:30 PM
Post by: Shark on March 19, 2005, 01:18:30 PM
QuoteOriginally posted by Steve Burnett
Okay then, its going to be:
235 x 40 x 17 or
235 x 45 x 17
What reason can you give me for going for one above the other?
Why not 235 front and 245 rear????
Sorry steve just spotted this.
Original 16" wheels and tyres are 225/50 16
Overall diameter is 24.86inches or 631mm
235/45 17
Overall diameter is 25.33inches or 643mm
A difference of +1.90% from stock
235/40 17
Overall diameter is 24.44inches or 620mm
A difference of -1.74% from stock
Remember school maths?
Circumference (i.e. rolling distance) = Pi x diameter
One full revolution of stock wheels = 1982mm
235/45 17 = 2020mm
235/40 17 = 1947mm
I went for 235/45 simply because Mazda used it and there willbe less tyre wear - marginal, but I\'m a tight git and 2% more miles from the rubber seems beter than 2% less.
The back wheels are where the speedo and odometer readings are taken from I think, but to use the same numbers for example
The 235/45 will travel further per revolution so the speedo will read lower than you are doing
The 235/40 will travel less distance so will read more than you are doing.
In both case the speedo inaccuracy will be approx 2% so not a significant error. Your choice really. The speedo can be recalibrated but will be a hassle especially so far from any specialists.
Again Mazda used 255/40 17 on the cars so I went with that.
Hope this helps - sorry for the maths lesson.
Title: Best size tyres?
Post by: Shark on March 19, 2005, 01:20:22 PM
Post by: Shark on March 19, 2005, 01:20:22 PM
Oh yeah, and 235 on an 8" wheel provides a little rubber beyond the rim giving a little protection for your expensive wheels.
255 on a 9" rim gives the same deal.
255 on a 9" rim gives the same deal.
Title: Best size tyres?
Post by: Steve Burnett on March 19, 2005, 04:03:38 PM
Post by: Steve Burnett on March 19, 2005, 04:03:38 PM
Mine are 8.5" wide front and rear.
Title: Best size tyres?
Post by: clive on March 19, 2005, 07:34:20 PM
Post by: clive on March 19, 2005, 07:34:20 PM
Hi Steve,
I know a few have answered this already but l found that by having
235x40x17 on the front it stops the tyres possibly rubbing the inner arches ( car felt better than when l had 45 profile on the front as well.
For the back you need 255x40 at least as this is the stock width and that way you will keep your spedo reading properly as well.
As John says 98+ RX-7\'s with 17\'s came with 235x45 front and 255x40 Rear from the Mazda factory, and although these cars were on 8" rims the extra 1/2" you have wont present a problem with these sizes.
So my recommendation is
235x40 Front and 255x40 Rear.
Hope this helps.
I know a few have answered this already but l found that by having
235x40x17 on the front it stops the tyres possibly rubbing the inner arches ( car felt better than when l had 45 profile on the front as well.
For the back you need 255x40 at least as this is the stock width and that way you will keep your spedo reading properly as well.
As John says 98+ RX-7\'s with 17\'s came with 235x45 front and 255x40 Rear from the Mazda factory, and although these cars were on 8" rims the extra 1/2" you have wont present a problem with these sizes.
So my recommendation is
235x40 Front and 255x40 Rear.
Hope this helps.
Title: Best size tyres?
Post by: MikeLMR on March 19, 2005, 07:57:20 PM
Post by: MikeLMR on March 19, 2005, 07:57:20 PM
better to have a narrower tyre on a wide rim than visa versa (within reason that is)