Need sound advice on TIRE UPGRADE!

[VXNIT]

Seeking new shoes, noticed after housrs of searching site threads that Nitto Grapplers are the prederred tire upgrade. QUESTIONs.
1. For my stock 18 inch 01 VX rims, will the Grappler 285/60/18 require any trimming? I do not want to trim anything on cladding.
2. Will 285/55/18 fit with no trimming?
3. Will 285/60/18 change speedo?
Thanks all.....

[Beavertractors]

I had my tires mounted today.You do not have to trim for 265-60-18..2 inches away from front cladding corner.They fill the wheel wells nice.Looks like it should have come with this size,maybe a little more offset on the wheels would look a little bit better. Total price with shipping, mounting,balancing,tire disposal,NY sales tax--$403.24 smooth ride and good looks-- Priceless Just in case they are still on sale at Tire Rack

[Raque Thomas]

The 285/55's are 2.6% too slow - when the speedo reads 60, you are actually going 61.6mph. The stock tire diameter is 29.6", these are 30.3". The 285/60's are 6.4% too slow - when the speedo reads 60, you are actually going 63.8mph. These tires are 31.5" in diameter. Check this site for more info:
http://www.miata.net/garage/tirecalc.html

[Moncha]

There's the Miata tire calculator and a couple of other ones listed in the Web Links Section

[tomdietrying]

Yep, the 285/60/18 changed my speedometer about 4.5 miles at 40 mph. Which means when my speedometer says 40 mph. I'm really traveling about 44-45 mph.

Correct me if I'm wrong, but I think the Nitto 285/60/18s require just a bit of trimming. They are just a hair bigger than the Yokohama AVT 285/60/18s which require no trimming.

Peace.
Tom