Hey guys,

I have a set of 16" FTR's (from the factory), currently they have 225/55/R16's on them. I'm getting a new set of tyres and want to know if I can fit a pair of P245/50/R16's on the rear? According to the catalogue i can cause it says this.

Tyre Size
P245/50R16
Service Descr.
96W
Speed rating
W
Approved Rim Widths
7.0-8.5
Measuring Rim Widths
7.5

Any thoughts? or do I need to stick with my 225's?

Saiken

Last edited by Saiken on Tue Oct 28, 2008 7:18 pm, edited 1 time in total.

245/55/16 will fit easy...... its the exact same rolling diamter of the 225/60/16 i fitted last week on the rears, but they wouldnt fit on the fronts.

However thats an unusual sized tyre, and if you ever needed a replacement it wouldnt be "on the shelf" and priced accordingly. I personally wouldnt go wider than 235 on a 7" wide rim

The 245 tyre your looking at will throw out the speedo by 4kph, which means your speedo will show 96kph when your really doing 100kph

A 235/50/16 will put your speedo out by 1kph, and a 235/55/16 will only make it 2kph off on the highway

A 245/50/16 will be spot on......

As for the fronts, anything over a 664mm diameter will be close to hitting the steering knuckle (whatever its called)

Couple things to think about
http://www.miata.net/garage/tirecalc.html

Sorry, i meant to say 245/50/16..... as it says in the spec's i posted lower.... but yeah.

so you say.... dont go bigger than 235's......

maybe ill stick with my 225/55/16's

225/55 is the "comfort" type/sized tire fitted to Fairlanes and LTD's with 16" rims. It is a bit of an odd size too.

225/50 is the factory fitment size for FTR rims, and there should be plenty of decent rubber out there at that size.

yeah 225/55 isnt a common size, but i'd still be more inclined to fit it over a 225/50 as it will fill the guards 12mm more and still keep the speedo correct, as the 225/50 is an undersized tyre compared to a stock 205/65/15 on base models

225/50/16 was the factory fitment on the XRs.

If you want to go wider, then a 245/45/16 is a close fitment in overall diametre.

There is a specific speedo gear for 3.45s and 16" wheels, being a Black 23 tooth cog.


Cheers
BenJ

My Speedo is spot on with my 225/55's so i would goto 245/50's..... except everyone said 235 is about the largest i should put on the 7" rims. So i've ordered another set of 225/55's.

The last tyre mob i went to said my 225/55's where an odd size and wanted to fit 225/50's.... but the car has always had this ratio, so i wont change it cause i've never had a speeding ticket (sit on the limit all the time) and when i pass by the speed limit signs that tell you how fast your going, they say the same as my speedo, and finally my GPS also tells me the same speed as the speedo.

** i was just curious to if i could fit the 245's on 7" rims, however it is obvious its out of the comfort zone.... so ill need to find a set of aftermarket rims i actually like...... eventually **

With regard to lowish profile road tyres . . .

On a 7" wide rim, a 215 is generally the best fit.
On a 7.5" wide rim, a 225 is generally the best fit.
On an 8" wide rim, a 235 is generally the best fit.
On an 8.5" wide rim, a 245 or 255 is generally the best fit.

A narrower tyre that those recommended will leave the rim and sidewall vulnerable, and a wider tyre will deflect more around corners (though it will have a softer ride due to the curved sidewall flexing easier).