i bought the mastercraft-hp avenger 225-40-18.-88h rated.i only put them on the back since my front tires are only 1/2 gone.this tire feels alot better to the road than did the dunlops that came on it .the H rating is good for 130m mph-i think that is plenty unless you to alot of track time .they only cost me $100.00 @,not bad considering the 225-45-18 -91w were 185 @.the only problem is do you think i can put 40's on the front?

 

I'm not too sure size 225-40-18 is good for the car. The overall diameter is almost 1 inch less than stock. With this tire size, when the speedometer reads 60mph, you're actually going 62.1. It's recommended that you stay within 3% of the diameter of the original tires, any more than this and there's a risk of brake failure. Compared to stock there's a 3.43% diameter difference. Something to think about...

 

pix please?

 

I just got my baby back with her new Kumho ECSTA SPTs. I paid $540 to TireRack for the set and another $139 to the local Goodyear dealer for mount and balance. I'm anxious to give them a good highway run this weekend.

Got the 245/40s. I know that the sidewall height and overall diameter is virtually identical to the stock size (within 1%) but they sure look like a lower profile. Optical illusion?

 

damn $139 for mounting and balancing. I get mine done for $60

 

yeah, i get mine done at a performance shop for $50

 

$45 here, 19"s.

 

how could this possible cause brake failure?

 

Check out www.1010tires.com or www.tirerack.com tech section. They have a tire sizing calculator that you can use to compare to the stock specs. I'm not too sure on the technical details but from what I understand larger variances greater than 3% compared to stock will confuse the braking system computers. In automatics, this will also confuse the transmission shift points, which can lead to decrease fuel efficiency.

Someone who's more knowledgeable should chime in.

 

i think the 'brake failure' refers to ABS (and possibly traction control and DSC systems) because the computer will have a slightly wrong idea of how fast the tire is spinning/slipping. i think the rx8 compares the front and rear wheel speeds, but to what effect i dont know.

so its a little strong to say 'failure', but what exactly happens will depend on the cars programming.

james

 

i have noticed the the dsc /tcs do not come on as often as they use to .but then again im not spinning the tires as much either.wider tires better grip.i'm going to take it to the track this weekend and see if my 1/4 mile times got any better, since i'm not spionning the tires and i can dump the clutch now.