I have read a couple of comments in the car mags lately that suggest or explain why larger wheel-tire combinations result in slower acceleration times. It seems the larger wheel-tire packages either weigh more, or put more weight as a percent of the wheels total weight out at the perimeter of the wheel and tire. This requires more hp to turn the wheel and results in less hp to the ground. In some cases, I have heard as much as 10 or 15 hp eaten up by the larger wheels and tires.

Anyone here with some real world experience of this?

 

Well I can honestly say that although I love my BBS LM's they do slow the car down there is no doubt at all about that. The car is simply more spry with the OEM wheels or even 17" 7.5/9" Volks that are much lighter and still provide an increase in contact patch over the OEM setup.

That being said I strongly considered selling off my LM's for a set of Volks but I just could not get my brain past the more superficial aspects like the way the car looks in comparison. This was after driving on the Volks for a week, they were amazing to drive on but simply did not make me smile like my LM's do.

 

I got light weight racing harts for this reason, but sometime which I would have got some nice 18" BBS RG-R's. They just look so purdy!

 

Moving to wheel/tire forum.

 

...where no one will respond further.

 

Hehe! Not my fault. That just happens to be where it belongs. If we let every topic into UTH just because where they belong doesn't get much traffic, we'll have all the "What color should I buy", "Who has a hardtop and why" and "Which is the best exhaust" threads in UTH. Wouldn't that be fun?

 

That's the exact same reason, why I didn't stay with 17" on my wheels. I could have gone with a lighter wheel. But I never plan to track this car nor do I street race anymore. So what is the point.

My car is a garage queen, take it out on a nice day and get away from everything else car. Who cares if I am a tad slower?

 

Bill, I found a thread that was in our local forum talking about this very thing. It even gets into some mathematical calculations. Have a look. It might be interesting to you:
https://www.s2ki.com/forums/index.ph...pic=265833&hl=
It starts off about tires but then gets into bigger rims and stuff further into the thread.

 

Slower to accelerate and longer stopping distances.The stopping distances can be minimized by going to larger brakes;but then again larger brakes add to unsprung weight in some cases

 

I got rid of my 18" BBS RG-R's for that reason, replaced them with 17" Volks for a definite improvement in acceleration.

All of the applicable 18" rear tires are larger in diameter than stock, which makes the gear ratio taller, which means slower acceleration.